|Athena||Bendix G-20 and
|Univac 1108||IBM S/360-67||IBM 1401||Site Home|
|IBM 7040||Hybrid Lab||G-15||Bogart||DEC PDP-10||CMU Photos from Chris Hausler|
Professor Patrick H. Stakem - Linux in Space Presentation - Sheffield October 2003
|Mark DiVecchio||MD05||markdsilogic.com||Its Mark on the left in this 1978(?) photo taken at the Trenton Computer Festival. (TCF home page). More photos on my genealogy web page.|
|Joel Platt||See below for 1967 photo.|
|Chris Hausler||JH37||jchauslerearthlink.net||Its Chris on the right in this 1978(?) photo taken at the Trenton Computer Festival. Read this short article about Chris' early days and how he ended up at CMU.|
Taken at son, Micah's, wedding Sep 2003.
See below for 1967 photo.
From last contact that I had with Jim - about 1972
Mar 2010: With the help of Roy Engehausen and the CMU Alumni Directory, we have found Jim. See emails below.
||Mar 2010: With the help of Roy Engehausen and the IBM employee directory, we have found Tom.|
|H. Roy Engehausen||HE01||r.engehausengmail.com||Here is a photo of Roy and me taken about 1966
(from my genealogy web page)
|David Chou||DC08||dchouu.washington.edu||Dave worked in the Comp Center. He sent me scans of several G-21 manuals. Links to those manuals are in the G-21 web page.|
|Bob McFarland||RM08||rm08alumni.carnegiemellon.edu||Bob, Dave Vavra and I worked together during 1970-71 at Management Science Associates. We were PDP-8 programmers for the scoreboard at Three Rivers Stadium in Pittsburgh and for the passenger information sign system for the Bay Area Rapid Transit System in San Francisco.|
The Athena cost about $1,800,000. when new, and weighed over 18,000 lbs when shipped. It spent most of its operational life at a missile silo. It was built by Sperry Rand/Univac, for support of the Titan missile.
The computer, declared surplus by the Federal Government, went to Carnegie Tech via the Pennsylvania Bureau of Surplus Federal Property. It was used as an undergrad project until 1971, when the former EE undergrad students (Athena Systems Development Group) orchestrated its donation to the Smithsonian. It joined a sister unit, the Atlas Mod I Guidance Computer, at the Smithsonian.
The architecture was Harvard; separate data and instruction memories were used.
A Frieden terminal with paper tape equipment was used with the Athena, as well as an operating console. An interesting feature, mentioned in the CalPoly section, is the mode "BattleShort". In this mode, referred to as melt-before-fail, the power to the machine could NOT be shut off.
The Athena used a massive motor-generator set with 440 volt 3 phase AC input. I hooked this up from the lab mains, and got the generator set going initially. When the generator was started, the building lights dimmed, and there was no question that the machine was on. The motor generator control unit (seen behind the console) weighed a ton, and the motor/generator itself weighed over 2 tons.
The last launch supported by an Athena computer was a Thor-Agena missile launched in 1972 from Vandenberg AFB in California. It was used on over 400 missile flights.
Unisys History NewsletterVolume 3, Number 4
Sperry Rand Military Computers 1957-1975by George Gray
Although many of the computers of the 1940s were developed as military projects, the use of vacuum tubes made them too big and unreliable for incorporation into actual weapons systems. The Eckert-Mauchly Computer Corporation built the BINAC in 1949 for Northrop Aircraft, but no one seriously expected it to be put into an airplane. The massive SAGE (semi-automatic ground environment) system built by IBM during the 1950s for the North American air defense system was for command and control, not for missile guidance. When vacuum tubes were replaced by transistors, it became possible to have computers of smaller size and greater reliability. The transistor was invented at Bell Laboratories in 1948, but it took several years of development to become suitable for use in computers. Bell Labs built the first transistor computer, the TRADIC (Transistor Digital Computer), for the Air Force in 1954. It used 700 point-contact transistors and 10,000 germanium diodes. (A diode is an electronic device which allows current to flow in only one direction.) Both of the two major computer development groups (St. Paul and Philadelphia) at Sperry Rand became involved in early transistor computer projects. Philadelphia became embroiled in the long and costly LARC supercomputer project for the Atomic Energy Commission. St. Paul, building on its early work for the Navy, became heavily involved in military projects.
The Athena computer had 256 words of 24-bit core memory to be used as a data work area and an 8192-word drum for the storage of the program and data items which did not change (constants). The Athena was completed in 1957. It occupied 370 square feet and weighed 21,000 pounds. Once in service, it was found to have a mean time to failure of 48 days, twenty times better than the original specifications. Since the late 1950s were the time of the perceived "missile gap" between the U.S. and the Soviet Union, the U.S. Air Force deployed the liquid fuel Titan as an interim measure pending the completion of the solid fuel Minuteman ICBM. St. Paul delivered 23 Athena computers to Air Force sites by the mid-1960s. In the late 1960s, the Air Force gave one of the original Athena computers to the electrical engineering department of Carnegie Mellon University. It was used for various class projects and later donated to the Smithsonian Institution.
CIT Student-produced documentation (list from Pat):
Athena Console User's Manual, 1970
A Technical Description of the New Monitor, 1971
Using the Athena Assembler, 1970/71
Tom Engelsiepen wrote:
Here is the 1970 version of the ASDG Console Users's Manual, and an Athena instruction set description from November 1971, that shows some of the newer additions.
|Well someone was pretty busy back in 1970 and 1971 adding a bunch of new instructions.
I compared the two instruction lists and I found these new instructions:
Transfer Character to Tape
Verify Paper Tape
Rewind Paper Tape
Read Paper Tape
Compare Constant Register
Compare Negative Register
Compare Negative Character
Skip if Greater
Skip if Equal
Skip if Greater or Equal
Skip if Less
Skip if Not Less
Skip if Less or Equal
Skip on Sense Switches
Skip on Reader Clear
Skip on Reader Selected
SKip on Teletype Ready
It looks like alot of paper tape handling instructions and a lot of compare instructions.
Does anyone remember who did these?
|Date: Mon, 29 Mar 2010 15:56:20 -0400
From: Glenn H Sembroski <sembroskphysics.purdue.edu>
Subject: Re: Athena Instructions 1970 -> 1971
I think I did one of the compare instructions for a physics electronic's lab project. Got an A. I think what clinched the grade was showing the instruction in operation to the lab instructor and letting him hit the power-on switch. That always worked. With girls also.
|From: "David A Vavra" <davavraverizon.net>
Subject: RE: Athena Instructions 1970 -> 1971
Date: Fri, 02 Apr 2010 14:26:54 -0400
I worked on a number of instruction changes/additions but frankly don't remember which. IIRC, C. Putney worked on adding the Bogart Typewriter to the Athena.
It's all becoming a jumble in time anymore.
|Date: Fri, 11 Apr 2008 23:28:26 -0700
From: Roy <r.engehausengmail.com>
James Pollock worked for IBM San Jose for a number of years. I think I last saw him in 2002 or so. He is not listed in the San Jose employee directory that I can access. It may be an unlisted entry. However, IBM San Jose is a shadow of its former self. The disk division was all sold to Hitachi around that time and that is where he worked.
|A few years later, Roy was able to find Jim's phone number on the CMU Alumni web site. I called him on the phone in March of 2010 and talked with him. He later replied via email.|
|Date: Wed, 10 Mar 2010 20:28:15 -0800 (PST)
From: James Pollock <jpollock1sbcglobal.net>
Subject: Email address and a pic
Thanks for tracking me down and the link to the web site. Very interesting stuff.
Here is a picture of a B-250 logic module to add to your collection of pictures.
|Date: Wed, 10 Mar 2010 22:17:52 -0800 (PST)
From: James Pollock <jpollock1sbcglobal.net>
Subject: Athena CMU History
If I have time this weekend I will check the attic to see if I might have some of my old documentation for the hardware changes I made.
I know I have some of the old computer printouts for a program I was writing on the CMU main frame (IBM 360 mod 67???) so it seems I might have some Athena stuff too.
|Date: Sun, 14 Mar 2010 23:45:08 -0700 (PDT)
From: James Pollock <jpollock1sbcglobal.net>
Subject: Athena Documentation
I was able to locate my Athena folder. Attached is a recreated copy of the keypunch instructions.
Here is what I have:
1. "Modifications Made to the ATHENA Computer (April - June 1969) by James R. Pollock C-MU" Five page document that outlines limitations of ATHENA hardware and the seven hardware modifications that were made to address them.
2. "Instructions for using the ATHENA KEYPUNCH" Two page document which is attached in PDF format.
3. "James R Pollock - Senior Project" This document details the attachment of the B-250 to the Athena to add storage. Twelve page report which includes block and logic diagrams.
4. "ATHENA INSTUCTION SET DESCRIPTION" Three pages of instruction definitions including the new ones I added and a fourth page labled "TYPEWRITER CODE" mapping octel numbers to typewriter characters.
5. "INSTRUCTION DESCRIPTION" These are two pages (5-40 and 5-41) from the original Athena manual T.O. 21-SM68-2F-6-1 dated February 1963.
6. Two handwritten notes from Mark DiVecchio to me and what looks like a draft copy of my reply.
7. Invoice for one carton of 7/8" wide paper tape dated 2/12/70.
8. Disassemly dumps of Athena routines and two handwritten partial index pages. The 16 pages cover MOVE, ISR, PUNCH, CORE LOAD, Find/Change, OP-Table, Core Dump, PRI-DD-PRT, Print 4 Char, ERR-T-BKS, DD, Sys. Sub. routines. Plus 11 other pages of unlabled dumps.
Regards, Jim (JP40)
|Date: Mon, 15 Mar 2010 16:14:44 -0700 (PDT)
From: James Pollock <jpollock1sbcglobal.net>
Subject: Re: Athena Documentation
The instruction set document I have appears to be the one I created to document all the new instructions I added in April through June of 1969. It has the new DRUM WRITE, JUMP TO SUBROUTINE, and indirect core addressing functions. It also documents the Teletype Input/Output sequences. It covers 33 instructions types giving OP Code, octel code, bit field usage, function and description for each. Seems to be all you need to write Athena code on the modified hardware.
Regards, Jim (JP40)
Modifications Made to the ATHENA Computer
(April – June 1969)
by James R. Pollock C-MU
The Univac ATHENA (used for Titan 1 missle guidance) is a small general purpose digital computer given to the school in 1966. Due to the computer's age (designed in 1959) and intended use as a secure military control unit, there were many limitations which prevented its use as an effective and efficient tool for instruction or research.
As designed there were only 256 24 bit words of magnetic core storage which store temporary quantities generated by a program. All instructions were stored on drum (8192 words) and executed from the drum. There were no instructions which allowed reading or writing on the drum. The drum was initially loaded by manually going into Load Program or Manual Load modes. In Load Program, a high speed 7 level paper tape reader is used to dump a program from the tape onto the drum. In Manual Load, instructions can be loaded by hand one at a time. All program input came from a radar set and output went to the guidance equipment or to a small adding machine used as a printer. The only part of the IO setup that came with the computer was the adding machine.
Some of the limitations:
1. Storage – only 256 words.
2. Not being able to read or write prevents having subroutines, using the drum for additional storage to supplement core, and having programs that can modify themself or other programs.
3. Loading a program is very difficult because there was no punch with the unit and 7 level is not standard (teletype punches are 8 level).
4. There is no way of entering information into a program.
5. The adding machine is very slow and prints only numeric characters.
6. There is no way of saving a program i.e. punching it on paper tape.
In an effort to remedy many of these limitations the following modifications have been made.
1. A. Added an Indirect Unconditional Jump. Jump to the drum location whose address is stored in the core address specified in this instruction.
B. Added an instruction which allows the Program Address Register(it contains the address of the next instruction to be executed) to be loaded into the Accumulator. These two instructions were added mainly because the micro commands were needed for Drum Read-Write and it was easy to make them into separate commands. They can be used for some types of subroutines.
2. A typewriter was installed to expand the output and provide an input device.
3. A form of Indirect Addressing was added. It was discovered to be very difficult to use the newly installed typewriter because there was no easy way of accessing large numbers of core locations without having an instruction per location to be accessed. Indirect Addressing solved this problem.
4. Added the two commands Drum Read and Drum Write. A special drum protect feature was also installed to keep one program from accidentally destroying another. The drum is divided in half with the lower half prevented from writing on the upper half. A program in the upper half can write anywhere on the drum. The idea is that system programs (fully debugged programs like general purpose subroutines, input-output routines, etc.) will be kept in the upper half and programs being worked on will be in the lower half.
5. A 7 level punch was salvaged from an old Digital Differential Analyzer, converted,and installed on the ATHENA as an output device. Programs can now be dumped from the drum on to paper tape for storage and later read in on the high speed paper tape readers. Programs can also be punched off line by hand.
6. A Jump to Subroutine command has been added. This makes it very easy to use subroutines.
7. A clear Accumulator and an Exclusive Or were added. Previously to clear the Accumulator a zero had to be stored in core and then loaded into the Accumulator.
With the modifications made so far and the ones to come the ATHENA should now be able to move from just taking up space in the E.E. building to being a useful instructional tool. It is doubtful that the ATHENA could be used as an effective research computer with its present dependence on a drum a relatively low speed storage device (even moving at12,000 rpm). Until more core is added and the execution of instructions occurs from core, the main use I see for the ATHENA is for instructional purposes. ( I presently have 8 - 4096 7bit core units that will be installed when I have the time and figure out the wiring.) I feel that a computer that students can program, run, and modify would be of great assistance in teaching them the fundamentals of computer design. There are several PDP-8’s on campus that could serve the same purpose but these are tied up with various projects. Taking a digital design course one may learn about the PDP-8 and write machine code programs but must run them on the Univac 1108. This does not really give the student the contact he needs.with the machine. If one were going to be a programmer then that is all the contact one needs but if one intends to design computer systems the machine is the important part.
(A pdf version of Jim's document is here.)
Photo taken by Patrick Stakem soon after the Athena was installed at CMU. This is in room 55A of Hamerschlag Hall on the CMU campus.Pat may have more taken at the same time. He wrote:
October - Athena installed at CMU.
This was before the computer was modified to give it more general purpose functionality.
|Date: Sat, 12 Apr 2008 10:07:10 -0700
From: Roy <r.engehausengmail.com>
Subject: Mark's web page
From the web page
"My understanding was that the Dept. Head (and I can't remember his name, preceded Jordan) had this thing for surplus stuff, and that's why we had the Bogart, the Athena, the big lathe that broke the granite steps, etc."
The answer is Everard M. Williams
IIRC every bit in every register appeared on the console. Each register had one clear button on the end and each bit could be individually set by pressing the lamp for that bit which was also a pushbutton.
Typical circuit cabinet showing the logic modules. Each of these metal modules was replaceable. Each contained a small number of logic elements. Like 2 flip-flops or 4 AND gates. Similar to the first generation of IC's. Photo taken about 1971.
John Yurkon wrote:
"One detail that isn't on the web page, but perhaps is in the manual, is that the transistor circuits were in cans pressurized with argon to keep the computer running under the most adverse conditions."
Motor Generator Unit
This teletypwriter was added by ??. A Frieden Flexowriter. It was the only human interface device (besides the lights on the console. Originally, the Athena came with an adding machine type of very simple output device. This Flexowriter came from the Bogart computer which was also given to Carnegie. Photo taken about 1971. Constants Unit.This could hold 8 constants which could be read by a running program.
Typical backpanel wiring in the one of the cabinets. Photo taken about 1971. Date: Sat, 15 Sep 2007 21:33:39 -0400
From: John E Yurkon <yurkonmsu.edu>
My involvement was helping to finish connecting the units and diagnosing why the RAM wasn't working. That turned out to be simply one unconnected power supply cable.
Control unit for the Motor Generator
Photo taken about 1971.
Power controlRight in the middle is the famous "Battle Short" button. The Athena ran on 208VAC, 3-Phase, 420 CPS (Hertz).
Photo taken about 1971.
Date: Sat, 15 Sep 2007 14:11:30 -0700
From: David Rodgers <dave_rodgersmsn.com>
Mark, et al.,
I started working on Athena when it first arrived: cables cut by ax, documents in disarray. We first figured out how to power the MG set and learned not to press the "battle short" button. Regards to all,
Another view of the console along with the Motor Generator control unit. Photo taken about 1971. John Yurkon wrote:
"Charlie, perhaps along with others, wrote a prime number generator for it. Writing any code for it was a chore because the speed of the magnetic drum was fast enough that it would pass by the next address before an instruction would complete. So, to maximize the use of the limited instruction space you'd have to sort of interleave the code and make sure you knew how long an instruction would take."
The raised floor of the Athena. The first cabinet on the left was the paper tape readers. Photo taken about 1971.
"I just looked at the site. Very very cool. I think the Burroughs computer was a B280. I have a couple of logic modules from it and a memory stack stuck away in storage some place. When I have time I'll send more info. For instance, I was the one who "decabled" the Athena so it could be taken apart and loaded on the moving trucks to the Smithsonian. That was a job that took me a good part of the summer (1972)."
Paper tape readers. This loaded programs into the 8K of drum memory. I originally wrote here that these were magnetic tape readers. Lauston wrote:
Mark, et al.,
The caption for the photo of the tape drive says, "Magnetic tape."
The manual says: "HIGH TEMP TAPE, DS123, figure 1-65, T,O. 21-SM6B-2D-6-1: Indicator Iamp which indicates a condition of high temperature in the perforated tape reader assembly". IIRC, it was originally paper tape, read by photo cells and sometimes there were light or oily spots on the tape that would get a false bit and could be corrected with marker. The tape in the picture is dark, but I think it is paper.
Later on 16 Mar 2010, Jim Pollock wrote:
On closer inspection of the Paper Tape Invoice I think it clears up the confusion on the Athena tape reader picture you have.
In the picture the tape looked very dark like magnetic tape but we all know it was actually paper. The invoice gives the reason in the description.
"1 CTN PAPER TAPE 8 IN DIA 7/8 IN WIDE 2 IN CORE BLACK OPAQUE, UNOILED"
So the paper tape the Athena used was actually opaque (black?)
Regards, Jim (JP40)
Chris quickly followed with:
I think we may have gotten the opaque tape because of problems with the oiled "yellow" tape. As I stated in that email a year or so ago, we did have to buy our own tape as it was 7/8" not the popular 1" stuff used on the Teletypes and minicomputers around campus. We bought a box of the yellow oiled tape in 67 or 68 when Dave Vavra wrote his Athena cross assembler which ran on the G-20 and punched tape on its PT-10. (Mark, if you want me to make a copy of the PT-10 service manual and mail it to you I will, I think I did send you a photo showing the "Bendix G-20" loose leaf binder in which it is stored.) However there were two problems with this tape and this was true with the minicomputer photo "high speed readers" I used in the 70's as well. Over time the oil in the tape coalesces into translucent drops which the photo readers "see through". I remember having to use black magic markers on this tape on the Athena to try (sometimes not successful as the tape was still translucent although now black) to get it to read. The other problem is that some of the oil transfers to the guides and pinch rollers of the drive and messes them up too. I know this was a major problem with the minicomputer readers I used in the early to mid 70's. The black unoiled tape gets around both of these problems (at the cost of wearing out the dies on the paper tape punches much more quickly). As a side note, about a dozen years ago the BNSF RR presented me with a DG high speed paper tape reader in excellent condition (installed in a late 1970's system by contract requirement but rarely used) complete with full technical docs. For a while I was thinking of interfacing it to a PC using the printer port but to date its still collecting dust in my shop :-)
The notes from Tom tell me something I didn't know either. I was always aware of two groups of folks who worked on the Athena of which as I earlier stated, I knew of the first group but I really only got involved with the second. Tom documents a third group of which I was unaware. Like Mark, I too do not recognize some of the names he lists. The groups did overlap some but each seemed to come at the machine with differing goals building on the efforts of the previous groups. Realizing I needed to focus more on graduating from CMU, I didn't have much to do with the Athena after 1969 or early 70 and when I went to work for the school in the CS engineering lab starting summer 1970, I had more than enough computer stuff to keep me busy and (maybe :-) out of trouble.
I'm not sure what this set of wiring and connectors were for. The logic was some form of RTL logic. Inputs were all through resistors and you can add more resistors to make bigger OR gates. I think the blue modules were resistor packs (??). Output of the gates were wired NAND?? Is that right? I seem to recall that if you wired the outputs of the OR gates together, you got the NAND function. That made is possible to build logic using multiple OR gates feeding a NAND function. Is my memory correct on this? Photo taken about 1971.
Tom Engelsiepen reminded me that diodes were used to expand the OR gates and that is was probably and AND function when wiring the outputs together.
The console of the Burroughs B-250 that became attached to the Athena. A senior project by Jim Pollock. Photo taken about 1971.
Dave Vavra wrote:
"The Burroughs was a B-250 IIRC."
Date: Sat, 15 Sep 2007 12:20:37 -0400
From: jchausler <jchauslerearthlink.net>
Subject: Re: Athena Systems Devlopment Group rulz!
What a blast from the past! Yes, Jim Pollock was the man who did the senior project. IIRC it was mostly built on a panel in the Burroughs B250 (yes it was a 250) which sat in the machine's cabinet on the front of the machine below the front panel. I recall helping to un-wire wrap the panel as I was sitting in front of the I/O desk in Scaife so Jim could do his circuit on. I recall that a number of folks helped with this effort. (I also recall the sore wrist I got doing this :-) I remember Pat Stakem and I leaving Jim drunk on the sidewalk waiting to be picked up for his flight back to California after graduation, the last I saw of Jim :-)
Although I have a fair amount of computer junk (junque, collectibles :-) from or about that period in my stash, the only Athena thing I have is one of those cordwood plug in modules from the B250, I believe a dual flop. From the late 1960's to the late 1970's it hung from the rear view mirror in whatever was my current car. Now, among some R series DEC modules, a single G-15 flop plug in (bought from Boston Computer Museum about 15 years ago) some DDP-516 modules and a few others, once a year it hangs from my Christmas tree :-) Other times it sits on the shelf in my family room among all the other trinkets.
About all I did for the Athena was to write what I believe was the initial "debug monitor" which used the Flexowriter as a console. The best I can describe this is that it was similar in concept to the early "debug ROMS" which came with some of the early micro-processors, like MIKBUG for the Motorola 6800. Anyway I called it "SHE" (somewhat helpful executive) and stealing a bit from the comp center named the associated routines "HER THINGS" (helpful executive routines, to help implement new and greater systems), the "things" part being what was stolen. Charley Putney (and yes, last I heard, he was in Ireland, I traded emails with him some years ago but seem to have lost his email address, he was working for Data Products IIRC at the time.) wrote an editor and assembler for the machine and I believe rewrote or expanded "SHE".
I seem to recall that over time there were sort of two groups, the initial group which included Dave Rogers and Walt Sullivan who installed the machine along with some others and then the later group with which I was more involved.
Remember the Flexowriter was something we added. The machine came with that little waist high box inside of which was what amounted to an adding machine with solenoids over each key. It would just print out numbers on (natch) a strip of adding machine tape. It was just used as a printer, its adding machine functions apparently being crippled or removed for the application.
Yes the Athena was installed in HH55. This was adjacent to HH53 where Gordon Bell had his office and the PDP-8 and G-15 were located.
The department head who tended to collect "junque" and got the Athena was Williams. I'd have to look up his first name. I believe he retired in 68 or 69. His replacement (one or more folks before Jordan) I recall did not like the Athena group and wanted it gone, I believe so he could expand (as was eventually done) the materials labs. Williams was also the one who got the IBM 7090 from Gulf Oil which sat in the halls for some time and whose motor generator set provided some entertainment for a few of us (remember turning it on the first time with the 10 foot pole from behind the HH53 door).
A fond memory I have of the Athena is the start up of the motor generator set. When running it just made a loud rushing air noise but sounded somewhat like a siren when starting up. I remember walking across campus in the middle of the night when things were otherwise quiet and even though the open windows in HH55 faced away from the campus (this was before we "stole" the air conditioner from HH53 after the G-15 had been removed) hearing the thing start up :-)
Ah, those were the days my friends, we thought they'd never end...
J. Chris Hausler
I think this is the insides of the B-250, a Burroughs computer that was interfaced to the Athena. The interface design was was a senior project by Jim Pollock. It actually worked. The claim to fame of this Burroughs computer is that it did decimal arithmetic, not binary. Photo taken about 1971. This was core memory unit that I, Mark DiVecchio, tried to add. It was my senior project. It never worked. The core was from the Bogart. Photo taken about 1971. I am somewhat amazed that this project sat, virtually untouched, from spring of 1970 until I took this photo and it probably remained untouched until Glenn Sembroski diassembled the Athena to ship to the Smithsonian.
From the Bogart Programmers Manual:
1. Core Storage
× This storage can retain 4096 24-bit words, a total of 98,304 bits of information
× The Magnetic-core storage contains 24 planes. Each 10 inch plane is a 64 by 64 square array of 406 cores. Three of the four wires running through each core write information into the core and the fourth wire senses whether a 1 or a 0 is stored in the core.
× If the core is magnetized in one direction, a 1 is stored in it; and if it is magnetized in the reverse direction, a 0 is stored in it. Information read out by applying a current to the two read-out wires drives the core into its zero state. If a 1 is stored in the core, the magnetic direction-change induces a voltage in the read-out wire. By sensing the voltage on the read-out wire, it is possible to determine the previous magnetic state of the core.
× Since the read-out wire sets the core to the zero state, it is necessary for the memory circuits to restore the core to a one-state. If it contains a 1, this is the regeneration portion of the storage cycle. The total storage cycle of read-out and information regeneration takes 20 microseconds per word.
Date: Sun, 14 Jan 2007 21:09:58 -0500 (EST)
Subject: Athena Systems Development Group
You may not remember me. I was a freshman at CMU in 1968 and left in '69 when my dad died. I was part of the informal ASDG. (I wrote a routine to move code from one part of drum to another.) I was doing a little nostalgic surfing tonight and came across your website with the above e-mail address as well as your resume that states that you own or owned a business by the name, Athena Systems Development Group. Did you partner with or employ any of the others that were in the group at CMU? I see you kept in touch with Pat Stakem. I cannot put a face to the name, but I remember the name. On my last trip home from Pittsburgh, I stopped to see Charlie Putney, who was in a car accident on his way back to campus and was recuperating in a hospital at the time. Last I knew, he was in Texas.
It was interesting to learn that the Athena that was at CMU went to the Smithsonian. I also appreciated the photo you have of the console in your website. I imagined that the machine went for parts or scrap metal and was lost to history. I wonder if it is displayed or stored in DC. I was given the ID, LS28, for access to the other mainframes at CMU. In a field where things can be obsolete in less than 40 minutes, it amuses me to use an ID that is almost 40 years old.
After CMU, I worked for Applied Logic Corporation in Princeton, NJ, for 3 years. It was a time-sharing business with a national phone network. We used DEC PDP-10's for mainframes and PDP-8's for communication nodes. I moved to Vermont in '73 and have worked for a small, family-owned dairy for almost 31 years. When they decided to begin to use computers, I selected the desktop and wrote the applications (Paradox). There just wasn't anything on the market that exactly fit our needs.
Cindy, my wife of 29 years, and I have four children. Our oldest, Andrew, is stationed at Camp Pendleton. We went to see him before he went to Iraq. We only saw San Diego in the dark because of the schedule for our flights in and out, but it seems like a nice city. Micah, our second, is in Ogden, Utah. Our daughter, Arla, is in Duluth, MN. We have yet to visit either of those places. Our youngest, Tim, is still home. We are a four time zone family.
No doubt this is much more information than you were hoping for when you got up this morning, but since you have much of your own on the Internet, I trust you value such things.
Lauston Stephens wrote:
Do you remember the name of the fella that implemented drum read, drum write and the interrupt on the Athena? He was from southern CA and, I believe, class of '69. He knew what he was doing and, as I recall, once did a little soldering without powering down the Athena. Being young and impressionable, I wanted to be just like him. There were some modules in the cabinet near the console on the window side of the room that were designed for I/O, relays or something along that line. Somehow, I was assigned/allowed to do a hardware modification in that area. No doubt, someone else wanted to do something else at the same time and I did some (poor) soldering with power up. Things did not work as expected. No doubt, I blew some components and have regretted my rashness ever since.
It's not like there were replacement parts at Radio Shack and plenty of money in the budget. Foul deed, I betrayed the trust granted me by my superiors and smote the goddess Athena a mortal blow.
Absolve me, Sir, for I am unworthy to speak of things Athenian.
Glenn Sembroski, class of '72, was my roommate for the fall semester of '69. He claimed that he had cracked the code for the Athena communicating with the Titan. I never asked him to show it to me and I don't know how substantial his claim was. There is a Glenn Sembroski at Purdue. It may be the same person. ITaP: Information Technology at Purdue
When a link is ready, as your page develops, there may be some things that come back to mind that I can contribute.
One possible page is the achievements of those in the group. You ran your own business and, if this is the same Glenn Sembroski, he has charted a stellar career. (Yes, pun intended.) There could be an argument here in support of such informal activities on campus. The engineers' answer to the dead poet society.
1967 Joel Platt and Dave Rodgers
Dale (who took the above photo) wrote:
The time spent with the Athena was a lot of fun. Every time we walked into the room, something new happened. We often pulled all nighters just because there was a lot to find out about the machine. The picture of Dave and Joel at the console is a good example. This is the first time they actually got a simple program to run. Excited and puzzled all at once.
|Date: Mon, 17 Sep 2007 18:27:20 -0400
From: Dale Dewey <dedrochester.rr.com>
Subject: Athena Missle launch computer
Dave Rodgers just sent me your eMail address and says that you are interested in the Athena computer. I was one of the original EEs at CMU who moved the thing into the lab and started putting it together. Some of the stories I can tell are rather amusing. Like trying to get the 400Hz MG set up and running. They required 440V AC 60 Hz and all we had were some pole pigs and 220. Almost blacked out the entire campus when we put power to the transformers and had two wired incorrectly.
Then there was the time it went into "battle lock" thinking a bird was in the air and we had no way of shutting it down without destroying everything. That took some trickery on our part.
Anyway, I would be glad to contribute to your work. I have six slides (five good) which need to be scanned into jpeg. I have one which is a poor scan of a print that you might find amusing. This was taken in June of 1967. I know Dave is one of the guys. I think the other guy (mouth open) was named Joel and he ended up teaching at CMU. Not sure about that though.
When I get the others, I will send them along as well.
|Date: Mon, 17 Sep 2007 16:25:44 -0700
From: David Rodgers <dave_rodgersmsn.com>
Subject: RE: Memories of Athena in pictures
To: Dale Dewey <dedrochester.rr.com>
I can see that the six-pack of 12 oz. Coke bottles is empty making the picture authentic!
I'm pretty sure the other guy in Dale's photo is Joel Platt.
|Date: Thu, 20 Sep 2007 15:44:03 -0400
From: Dale Dewey <dedrochester.rr.com>
Subject: More on the Athena
Thought I would sit down and capture some of my memories of the Athena. Attached are my ramblings. Feel free to edit and correct.
I think this is fairly accurate but then it was 40 years ago. Some things change and others don't. More pictures. These are probably the earliest ones of the Athena when it arrived in early 1967. The date stamped on the slides I have is June 67, so the pictures were taken before then. If you would like the slides, you are welcome to them. Seems you are becoming our archivist.
Yes, I also had a set of keys like yours. I remember the long flight of steps leading from the first floor down to the lower entrance.
My Memories of the Athenaby Dale Dewey, 20 Sep 2007:
Wandering back in time to 1967, there were a few senior electrical engineers who had focused on digital electronics (aka computer science) rather than the popular analog/radio/material electronics that was main stream for the day. We were small in number. Who knew then that we were on the verge of a great digital revolution in our careers? Ah well, these seniors needed a project and it seems that the Carnegie Institute of Technology (CIT, not CMU until 1968) had just been given a computer by the USAF. My first memory of the computer was moving the MG set from the delivery truck into the lab.
We had to load it on the freight elevator to get from dock to lab. Being seniors, we were foolish and did not pay any attention to the load capacity of the little elevator. The MG set was half way onto the elevator and it started to fall. Fortunately, it stopped after dropping about 4 inches. We then blocked up the end on the elevator (making it level with the floor) so we could finish loading the generator (more ignorance). One of us rode the elevator down three floors to the lab. Fortunately, it stopped level with the floor and we quickly unloaded the MG set. From notes here, the thing weighed in at 2+ tons. Can you say large SUV? We got lucky but then luck was always on our side as we continued to put the Athena back together for the first time.
When we started work on our senior project, you could tell that the thing had been in storage for a long time. As seen in some of the pictures, there was dust everywhere. The raised floor was assembled, all of the cabinets were placed on the floor and there were piles of cables and many volumes of manuals and documentation. As a team, we spent a lot of time organizing the manuals. Fortunately, the USAF always numbered everything with sequence numbers. I am not sure we knew what every volume was but once we found the index volume, we could find anything. There were hardware manuals and software manuals. My job was hardware. Get the thing running. When the computer was removed from the silo, all of the power cables in the cabinets were cut with bolt cutters (they were attached with robust screws to large buss strips). Fortunately, the data cables uncoupled from the cabinets quickly.
I started sorting out the power cable connections and removing the old screw terminal connectors. We needed to get new terminals and new connections to the power cables. Each wire was labeled and there was a manual with a wiring diagram. This wiring task took about two weeks to complete. Another job was getting the MG set running. It required 440VAC, 60Hz, 3 phase. The only power we had available without going into the distribution cage was 208VAC, 60Hz, 3 phase. Enter our course on “Electro-mechanical energy converters”. Who knew that we could get a quick, practical application of one of our undergrad courses? Using a large number of 1:1 isolation transformers mounted on wheels, we patched together enough transformers to give us the required voltage.
When we felt all the cables were properly connected, we threw the breakers with a broom stick and “POW !@#$%”. The entire lab went black. It seems that we missed one of the dot markers on the transformers and effectively created a grand phase short, embarrassing but quickly fixed. We replaced all the fuses and tried again. The lights dimmed but at least we had 440. Learning our lesson, we were now more cautious and created test plans for the MG sets. There were actually two sets, one primary and one backup. We tested each and switched loads back and forth. The MG control cabinets were very large by their own right. These were actually very sophisticated MGs. The frequency could be adjusted. Notice the reed meter in the photograph. There was also a voltage stager. All power supplies had to be brought up in proper order so as to bias the transistor circuits properly. If this was not done, the transistors would be fried.
We probably spent a month going through a number of power up and power down sequences manually. We were very cautious and learning all the time. Finally, the big day came when we felt confident that we could let the whole thing go automatic. The MGs came on line, they were up to speed, frequency and voltage were spot on, the sequencer was staging and the power to the cabinets was coming on line, celebration with another Coke. Then the console lit up and we really felt great.
It had been a long night. It was time to shut down and get some sleep. Wait, what is this thing called “Battle Lock”? It was apparent that the computer was delivered with a full load of software. When the system started, we essentially did a cold boot and the program on the drum started running. Now we knew why the console fired up. There was no way of shutting down the power sequencer. Remember that it needed to start up in proper sequence? Well it also had to shut down in reverse order. We could not even shut it down manually. Pull the domestic power? Not on your life! Can you imagine the arc you might get under full load?
This is when we kick into emergency mode. Where is that manual with the index? Look for “Battle Lock” and find out what is wrong. “Battle Lock” – A bird in the air! Yea, right, we just launched a Titan? Now how in the world would this thing think a bird was in the air? More digging into the wiring diagrams and we quickly found that there was something missing. The feed from the ground tracking radar was missing. The programmed assumption was that it was destroyed and the bird must be maintained regardless!
Where was that data input cable anyway? Oh ya, it was under the floor next to the cabinet against the wall with all external interface buffers. There was only one way in, crawl! One of the guys grabbed my ankles and in I went. After about fifteen minutes, I found the connector in a bunch of cables and quickly applied a short to two pins. The radar was back on line, there was no telemetry, no bird in the air, no battle; reset the “Battle Lock”. At last, we could now shut things down in an orderly manner.
Now that we had control of the hardware, it was time for the software guys to move in. They played with the registers, wrote simple addition and multiplication routines, played around with the lights on the console and generally had a ball. It was now getting to the end of our year and exams were at hand. Work on the Athena stopped for the summer and my guess is that it started up again in 1968. I had lost track of the project at that time and was now off to cleaning up some courses and getting to work (and money) and Eastman Kodak Company. While that is another story of 38 years of experience, I still remember the long days and nights with good friends.
Here are some of the more hardware techie things I remember about the machine:
|Dale Dewey wrote: The
girl in the photo is a mystery. I remember that she was someone's girl
friend. Not mine however. We might get a hit once it is posted on the site. Dave Rodgers might remember.
Dave Rodgers wrote: The girl in the photo with Joel Platt between the cabinets is Diana Patterson, girlfriend of Walt Sullivan.
|From: Patrick Stakem <PStakemloyola.edu>
Date: Mon, 8 Mar 2010 15:25:33 -0500
Found 6 slides, developed but unmounted, of Athena. Looks like the period when we were assembling it. Have them mounted, and ready to scan. day or two. Not real good quality.
In picture "Athena 5, note the 7094 console"
The second, third and fourth of Pat's new photos as displayed on the web site were taken in HH53 after the G-15 was removed. Thus I can guess that these were taken in 1968 or 1969 as the G-15 was still in place (although not working very well) at least into fall 1967. You can see the cut off end of the exhaust duct which had been previously used to cool the G-15 in the top part of the first two of these three photos. Further, they also all show some parts of the IBM 7090 behind the B250's.
(More of Chris' comments are below.)
Pat said these large cabinets in the rear might have been part of the 7094: "we had a couple of IBM-blue cabinets, cpu but I don't think
The fifth photo obviously taken in the Athena room shows the IBM 7090 console desk. I had forgotten that we had moved it in with the Athena.
The 7094 came from Gulf Oil, downtown. Part of the"heck, yes, we'll take it if it's free program." I hooked up the motor generator, and was running it when the bearing froze. The cabinet tipped over, almost making a new door in the wall. I believe it was scrapped, because we didn't have the core modules or maybe the disks - Gulf Oil kept them when it upgraded. I have the console.
|OK, I probably should
have turned these in after I graduated but with them, I was able to
access the Athena until it was shipped out to the Smithsonian. Keys are
401 - this was the Ham Radio station W3NKI on the top floor of Hamerschlag.
55A, HH53, 50 - I need help with these three, I think one was for the room where the G-15 was, one was the big lab outside of the Athena Room and the 55A must be for the Athena room itself.
MH ENT - Machinery Hall Entrance - this was the 3rd(?) basement door to Hamerschlag which went out to the parking lot toward Scaife Hall (it was Machinery Hall before it was renamed for 1st CIT president, Arthur Arton Hamerschlag in 1965). Do you remember that the end of Hamerschlag Hall which jutted out into Panther Hollow had a "prow"?
What are the odds that some of these still work!
|From: "Mark DiVecchio" <firstname.lastname@example.org>
Date: Wed, 23 Dec 2009 16:18:43 -0800
Subject: Cabinet next to Athena Paper Tape Drives
I was looking more at the two photos that Ray Carson sent of the Athena room.
One photo shows a view of the open door of one of the paper tape readers. To the left of that cabinet is another cabinet, not quite as deep as the tape reader cabinet. It looks to have some sort of front panel (with buttons or lights) on the left hand side.
This cabinet also appears on the 'official' Univac photo at the top of the page.
It does not appear in a photo that I took in 1971 which shows a rack of equipment in the same spot. (this is the photo titled "The raised floor of the Athena").
I don't ever recall seeing a green Athena style cabinet at that spot. Are my brain cells dying even faster than I think?
This is a truly fuzzy memory but I believe that unit is the "simulator". I have no actual knowledge of it but recall hearing that it could be used to simulate missile flight to the computer to test out its operation. I have this fuzzy memory that it was called the "radar data simulator". I have a somewhat better memory that since it performed no useful function as far as the ASDG was concerned, it was the unit stripped for parts both for replacement of failed modules within the machine and the push button / lamps on the console as well as for all the modifications which were made to the hardware. As I had nothing to do with any of the hardware mods, this all is at best a vague recollection.
73, Chris Hausler
|This is my memory also. And for some reason I think it was moved over to the opposite side (left of the console as you face it).
Your memory is correct. It simulated radar data by reading paper tape. IIRC, some of its logic was also converted to control the paper tape reader by a program.
Added Frieden Flexowriter as human I/O device.
Added drum read/write via instructionsFrom: "J. Chris Hausler" <jchauslerearthlink.net>
Date: Wed, 24 Feb 2010 11:47:52 -0500 (EST)
I was recently reviewing the web page and realized that unless I am wrong, there is one hardware mod not mentioned and an important one. I believe it was one of the first ones done, right before the "group 7" change was done, and like the group 7 change, done by Jim Pollock. Remember the Athena was a Harvard architecture machine, a program could not modify itself. As delivered there were only two ways to change the contents of the drum, either by initial loading a paper tape or by using the pushbutton lights on the console, both, of course happened with the machine halted. The important mod was to allow a program to change the contents of the drum.
Without that change, SHE wouldn't have been able to provide a way of viewing and patching the drum locations from the Friden. I certainly don't recall the details, but if you wanted to do a store to a drum location, you had to wait for that location to come under the heads. I know certain operations such as shifts took longer than one address increment time of the drum so you had to leave spaces on the drum as the next instruction to be executed after the shift would be whatever one was next under the heads. I believe these newly added instructions (basically a load and a store), however, "froze" the machine until the appropriate location came under the heads and then froze it again until the instruction immediately after the load or store came under the heads and then continued executing.
But this is a very fuzzy memory. I keep hoping that we will somehow get into contact with Jim who could possibly clarify some of this.
Added interuptsDon't remember who did this
Paper tape readers under program controlChris wrote: As received, the Athena paper tape readers would only load programs in an IPL environment. Someone did figure out how to put the paper tape readers under program control and the machine was so modified. All I recall of this is that it used the former "Radar Data Register" to pass tape data into the machine.
Group 7 type InstructionChris wrote: Another mod to the machine was to take one of the now useless instructions and model it after the "Group 7" opcode on the PDP-8. This instruction only referenced the ACC, IIRC, where individual bits in the instruction each had a function and certain ones could be combined (i.e. one bit would cause a one's complement and another bit would cause an increment and combined you got a two's complement "negate". I don't recall who did it.
|Date: Wed, 10 Mar 2010 18:06:22 -0800
From: Tom Engelsiepen <te04sbcglobal.net>
Subject: Re: Univac Athena at Carnegie Tech
Hey, you found me! That's a great site. I can certainly contribute some stories about the Athena, since I spent many, many hours in that room.
I'll send you a longer note after I dig through some of my old junk. I've still got some Athena documentation and program listings.
|Date: Fri, 12 Mar 2010 01:44:26 -0800
From: Tom Engelsiepen <te04sbcglobal.net>
Subject: Athena stories
I was an EE student, class of '72, and joined ASDG some time in 1969. I spent a lot of time playing with the Athena, mostly with software, but I also did my share of wiring and soldering. It was like having a personal computer, back when computer time was hard to come by. What better way to learn how computers worked than by getting out a soldering iron and wiring in a new instruction?
Some tidbits about the Athena's hardware:
Drum storage: 8192 17-bit words (programs executed from this)
Core storage: 256 24-bit words
Instruction time: 40 usec (broken into 8 steps)
Drum rotation time: 5 msec (Mark's note: 12,000 RPM)
I'm a little fuzzy on the details, but I think that most of the modules (cans) were set/reset flip-flops, which had a corresponding light/button on the console. Maybe some cans were sets of inverters. Outputs were "wired and" so that you could tie two together to form an and gate. The cans had multiple inputs that were or-ed together, but sometimes these were all in use, so you had to add an input splitter. This was a pair of diodes that allowed two outputs to be fed into one input (not really up to military spec, but it worked for us). Typically, this was done by sticking the diodes into a computer card and dangling it by the wire from the input.
I don't remember exactly who worked on what, but we had quite a few accomplishments during the years that I was there. First, here are some of the hardware changes that we made:
This was done before I got there, but it was rather important since originally programs could not be modified while running. Now we had a drum write instruction, and a JMS instruction that would allow subroutines to be called by storing the return address in the first word of the routine so that you could jump to it at the end.
The machine had several registers with names like "steering" and "vernier" that didn't do anything because they were supposed to be hooked up to a missile and, unfortunately, we didn't get any missiles. We turned one of these into an index register, which made it much easier to clear a range of memory.
Another useless register was turned into flag bits that could be individually set or tested.
Paper tape control
Originally, you would load a program from paper tape by dialing in a number on the console and pressing the read button. The hardware did the rest. We fixed this so that a program could initiate the read, and also rewind the tape.
I think it was Tom Wadlow who added instructions for loading and storing data one character at a time, which greatly simplified I/O routines. He also worked on the Flexowriter interface and really souped up the performance.
The original Athena to Burroughs memory transfer hardware was a marvel, which could move the whole Athena memory under hardware control in one gulp. Unfortunately, we could never get it working, so we abandoned that and made a simple byte-at-a-time interface.
Paper tape punch
Why did we care about transfering data to the Burroughs? Because we found a high-speed paper tape punch and it was easier to build an interface for it on the Burroughs. This can be seen sitting on top of the Burroughs in one of the pictures on Mark's site.
Second motor generator
When I got there, only one of the MGs worked. One day someone (I think Bernie Luksich or Jim Chew) decided to get the second one working. The Athena came with great documentation, so he just followed the troubleshooting procedure, and replaced some burned out diode or SCR and got it working.
On the software side, Ken Corbin and I did most of the work. Here are some of the projects (I still have program listings for all of these):
I wrote an assembler that ran on TSS/360. Object code was punched to paper tape using an ASR33 Teletype, but this wasn't compatible with the Athena's high speed reader. Instead, the code was loaded using the Flexowriter's reader, and then transferred to Burroughs to punch on the high-speed punch. Or sometimes we'd just sit down at the console and enter programs in binary from the push buttons.
SAM - Swapping Athena Monitor
Ken wrote this, and it was pretty sophisticated. "Swapping" refers to dynamic program relocation. The assembler would output a table that told which instructions were relocatable, so SAM could move a program around on the fly. This was needed because the paper tape hardware would load at a fixed address, so if you wanted to load more than one program, you had to move the first one to make room for the second. The main feature was a command interpreter that allowed you to load programs by name from tape, show a directory of what was available, and run them. It also had I/O and file utilities.
DDT - Dynamic Debugging Technique
Ken wrote this one too. From the terminal, you could dump or patch programs (including symbolic entry and display of assembler instructions), insert breakpoints, single step, etc.
Some games that I wrote.
I came up with this. I guess this was my first "video" game (not counting Space War on G-21 scopes, but that's another story). Back in those days, it was hard to get really interactive with a computer, but the Athena could do it. The Pong game worked by lighting a bulb in the middle of the accumulator register. Each player had a push button, and if you pressed it the light started moving. Every press or release by either player would change directions, and speed would increase. If the light reached your end of the accumulator, you'd lose a point, with score displayed in one of the other registers. I thought it was interesting that, in the panic of frantic button pushing, you could sometimes stop completely and the other player would continue pushing and releasing, and end up beating himself.
Floating point library
I wrote this, but never got a chance to use it for anything.
Besides program listings, I also have a document that starts like this:
ATHENA SYSTEM DEVELOPMENT GROUP
CONSOLE USER'S MANUEL
JUNE 25, 1970
EDITOR: BERNARD LUKSICH
TECHNICAL CONSULTANT: CHARLES PUTNEY
AUTHORS: MARK DIVECCHIO AND GLEN SEMBROSKI
FIRST PRINTING: JUNE 25, 1970
COPYRIGHT 1970 BY THE ATHENA SYSTEM DEVELOPMENT GROUP.
REPRODUCTION IN WHOLE OR IN PART WITHOUT PRIOR WRITTEN
CONSENT OF THE COPYRIGHT HOLDER WILL MAKE THEM UNHAPPY.
I'll finish with two of my favorite things to do with the Athena:
-- Start a program going and switch to slow rate (with speed controlled by a knob). Then shut out the lights and watch the blinkenlights.
-- Bring in someone new and get them to push the power on button.
|SHE "Somewhat Helpful Executive" by Chris Hausler|
|Assembler by Dave Vavra He wrote:
I wrote the assembler. It ran on one of the Comp Center machines but I can't remember which one. Probably the G-21. Whatever it was, it had a high speed paper tape punch. The tape had to be hand wound onto a reel that the Athena used.
I also seem to recall hand entering assembly like code using the Frieden. Don't know who developed that. (Or was that Freiden? There's a German company, BG Frieden, so I used that spelling.)
John Yurkon replied:
It's been a long time. I heard from Charlie a number of years ago, to my surprise. I don't know how he tracked me down. Search engines were just starting to mature.
When I left CMU the transports on the paper tape drives were working but they were still trying to get them to read properly.
I thought that the Bendix G-21 was being decommissioned back then. They were having a difficult time finding replacement germanium transistors and the disk storage looked kind of scary. The platters were bouncing up and down about 1/8" if memory serves.
I don't know of another machine that had a paper tape punch though. There was a water cooled monster that I never new the name of and there was an earlier Bendix G series that had vacuum tubes and was about the size and look of a refrigerator.
The Bendix G-21 and the Philco display units were what tempted me to get into trouble academically. I survived after a few years in the Air Force and ended up in the Honors Tutorial Program in Physics at Ohio U. Their computer facilities at the time were primitive enough to keep me out of trouble.
I know this group is about the Athena, but if anyone has a timeline for the history of the Univac 1108, the IBM 360 (mod 60 I think) and the Bendix G-21 at CMU I'd be very interested in hearing it.
Come to think of it, weren't there some PDP-8's that had paper tape drives? Could that be what you used?
Long time indeed!
The refrigerator sized machine was the Bendix G-15. Don't remember the water cooled one. The Bogart, maybe? It was in the same room as the G-15 IIRC. That used 6146W tubes in its flip-flops. I had a Drake 180W transmitter that used 6146A's just to give you an idea of the possible power draw. I get the impression from some of the web sites that the Bogart and Athena were somehow cousins.
(Mark's note: look at this Sperry-Univac Computer Genealogy.)
Got me in trouble too. I worked at a market research firm in Pittsburgh run by an ex-GSIA dean for a while and got to do some nifty things unrelated to market research like stadium scoreboards and the passenger signs for BART in San Francisco. Almost became Hausler's competition by working at Union Switch and Signal but took a small sabbatical and visited Southeast Asia instead. Came back in 73 to finish things up. Pat Stakem got me fixed up with a small NASA contractor here so now I'm designing and building flight software systems for spacecraft and coming up on 33 years.
Funny how things work out.
Date: Sat, 22 Sep 2007 11:57:44 -0400
From: jchausler <jchauslerearthlink.net>
Subject: Re: Details on Website
David Vavra wrote:
> I wrote the assembler. It ran on one of the Comp Center machines but I
> can't remember which one. Probably the G-21. Whatever it was, it had a
> high speed paper tape punch. The tape had to be hand wound onto a reel
> that the Athena used.
Dave, it was the G-21. It had a high speed paper tape reader (optical) and punch unit, the PT-10. Remember, the Athena did not use the common 1 inch 8 level paper tape used by the minis and the comp center teletypes but 7/8 inch tape (7 level but I think the Athena only read 6, three on each side of the feed hole). As a result we had to buy (shudder) our own tape. The PT-10 was adjustable and would punch 5/8 inch 7/8 inch and 1 inch tape. I know this because someone (it must have been you :-) had borrowed the PT-10 Service Manual and it was in the Athena room. One day when I entered the Athena room, after the G-20's had been removed from the comp center, I saw the PT-10 manual in the trash, someone was cleaning up. Dumpster diver that I am, I picked it out. I still have it in my collection of Junque. It includes basic programming instructions for the device (a Digitronics optical reader and a Teletype BRPE punch packaged each with tension arm spoolers.) and I'm assuming that you used that information to set up the device. At the time no one else was using it and you were likely the last user of it.
> I don't know of another machine that had a paper tape punch though. There
> was a water cooled monster that I never new the name of and there was an
> earlier Bendix G series that had vacuum tubes and was about the size and
> look of a refrigerator.
The earlier Bendix G series was the G-15, the size of a large refrigerator. It used 5 level (5/8 inch) paper tape. There's one, last I looked about 9 years ago, in the Smithsonian. In the early 90's I bought a G-15 plug in module from the then Boston Computer Museum. They were selling them in their gift shop IIRC. The G-15 was one of the most popular mid 50's small machines. I recall reading an article in a late 70's trade publication celebrating 50 years after the introduction of it and calling it the first personal computer :-)
Someone mentioned Joel Platt. I saw him last at the homecoming in 1997 at the engineering (or maybe it was just the EE dept.) reception. And of course, Pat has already chimed in with "DP".
|Athena resident assembler
Chris wrote: We've already talked about Jim Pollock's interface between the B250 and the Athena. What with the loss of the G-20 and Dave's program, someone (and I think it was Charlie Putney) wrote a resident assembler for the Athena. But there was still the need to punch tape for the Athena's high speed readers. I don't remember what exactly it was, but on the bench in HH53 were a bunch of small "green things" which were appendages to some kind of I think analog data analyzer. This had been there next to the G-15 and I believe was no longer used when I showed up in fall 66. One of these boxes was a paper tape punch. Someone interfaced it to the B250 and then using Jim's interface, Athena program images could be sent to the B250 and then punched.
|Date: Wed, 07 Nov 2007 08:23:36 +0000
From: Charles Putney <chputneygmail.com>
Subject: Hello from the past
Sorry for the long delay. The web page brings back a lot of memories.
On the Athena, I remember working on a program for a neural net simulator. It was my project for my course in Cognitive Psychology. The input neurons were connected to the console buttons and the output neurons were connected to the console lights. The intermediate neurons were randomly connected. Then, there was a punishment/reward scheme where if the output pattern was desired, the neurons creating this pattern would be "rewarded" otherwise you could "punish" the net and some of the offending neurons would be randomly scrambled. At the time, this program was a little too hard for me and a lot of it was written by Tom Engelsiepen. He used a cross compiler to write this, and the compiler was written by Ken Corbin. I have lost touch with these guys.
I'm retired now and my job career was: Texas Instruments -> Becton Dickenson -> Dataproducts -> Hitachi Printing Systems -> Ricoh Printing Systems.
Here are some of my recent interests:
18 Quinns Road
|Getting the Athena running.|
|Mark DiVecchio attempted to add 4K of core memory. Never worked.|
|Jim Pollock interfaced the Athena to a B-250 computer.|
|Date: Thu, 27 Sep 2007 07:22:52 -0500 (CDT)
From: "Lowell A. Benson" <labensonusfamily.net>
Subject: RE: Athena
Mark: Thanks for your feedback about our site. I plan to insert a link to your site when I next update our LEGACY site. I've also forwarded your URL to our committee (includes one of the original Athena hardware design engineers and one of the programmers who was at the Cape during many of the Athena controlled launches.)
I'm attaching a copy of a logbook page from an Athena launching site, I'm not sure which one - it shows the last launch as a Delta 8 on 7 March of 1962. This came from one of our field service engineers.
A few comments about the 'Battle Short' switches. Beginning in the early 50s and well into the 70s, military computer specifications required over temperature sensors with automatic turnoff to keep equipments from 'melting' if their cooling systems failed. If it was war-time and the system was involved in a battle, an operator could press the the switch to bypass the automatic shut off system. It was more important to continue the war time mission than to save the hardware to fight another day.
Lowell A. Benson, see www.usfamily.net/web/labenson for Legacy Pages, AHS '56 page, projects, and photos.
|Date: Thu, 10 May 2012 23:10:50 -0500
Subject: Univac Athena
From: grady early <bbtempranogmail.com>
Does anyone know what happened to each of the 23 Univac Athenas delivered to the Air Force?
I know what happened to the one donated to Southwest Texas State College -- scrapped.
|From: Mark DiVecchio <markdsilogic.com>
Subject: Professor Charles H Beck
Date: Mon, 23 Nov 2009 13:40:31 -0800
I got your email address from the Tulane web site.
Back in my college dates (1966-1970), my school, Carnegie-Mellon University got an old computer donated by the US Air Force.
It was called the Athena and was a guidence computer for the Titan I missile. Well a bunch of us students got ahold of it and it became our "personal computer" of the era. Of course, it weighed several tons so you couldn't take it class.
I've started a web page about the CMU Athena at: http://www.silogic.com/Athena/Athena.html
There were maybe a dozen or more of these computers given to schools across the country. We have a 1967 letter from an Athena Users' Group that was formed. In that letter, it mentions that the secretary of the group was a Professor Beck of Tulane. Searching on the Internet, I've found a Charles H. Beck who was involved with other old, cast off military computers.
Based on this letter, I assume that Tulane also had an Athena. Do you know if Professor Beck is contactable or do you know of anyone with knowledge of the Athena at Tulane?
It would be great to gather more history about the Athena Computer.
Thanks, Mark DiVecchio
|Subject: Athena computer - Professor Charles H Beck
Date: Mon, 23 Nov 2009 16:15:15 -0600
From: "Guedry, Candise A" <candytulane.edu>
Cc: "Cahill, Bill H" <cahilltulane.edu>
Unfortunately, Dr. Charles Beck has been deceased since October 12, 1994.
The only person who comes to my mind who is still at Tulane and who may be able to assist you is Bill Cahill. Bill is someone who has worked in computer technology at Tulane for a very long time and may know something about the Athena computer. I have copied Bill on this message for his response.
|Subject: RE: Athena computer - Professor Charles H Beck
Date: Tue, 24 Nov 2009 08:34:35 -0600
From: "Cahill, Bill H" <cahilltulane.edu>
Hi Mark and Candy,
I remember hearing about the Athena but it was always second or third hand information. I wish I could help. There are few old-timers around and I guess I'm one.
Subject: Great Athena site
Date: Fri, 19 Dec 2008 07:35:48 +0000
Just wanted to drop a quick note of thanks for your Athena site -- it brought back some fond memories of the installation we had at CalPoly, San Luis Obispo, CA, in the early 70s. Ours had a huge backlit plotter that had both a pen and an alphanumeric print head on it. The print wheel anticipated those to appear later from Diablo/Xerox.
I've attached a photo of our console.
Thanks again, fun times!
|Here is an excerpt from the CalPoly web site:
The next computer was a Univac missile guidance computer. It, too, was solid state and cost the U.S. tax payer over $5M (in 1998 dollars). It was an unusual machine in a number of aspects. It had two consoles, the one located with the tracking equipment and used to guide the missile and another maintenance console where every flip-flop and register could be viewed and set or reset manually. We only got the maintenance console which was very useful in teaching computer architecture. It was extremely reliable (no failures in the time we had it) and it ought to have been with gold plated contacts and with the PC boards hermetically sealed in stainless steel cans. It also had a "battle short" button which we, evenetually, learned was pressed 5 seconds before a missile was launched - it bypassed all the fuses and circuit breakers in the machine - the machine would melt down before it would quit!
Thanks for your email.
You are first person to contact me that had one of the Athenas. I really appreciate the photos.
Our web site is fairly new. I got an email from one of the guys and then some photos and then other emails and the web site just grew.
May I use your email and photos on our web page? Do you have any more that you can share. It would be really interesting to see how other Athenas were "used" by students.
Yes, you have my unrestricted permission to use my letter, photo, and any communications we have. For the record, I am the creator of the photos. (I'll upload them to WikiCommons when I get a chance.)
I may have some class notes, but most of my paperwork was lost in a basement flood long ago.
|From: "Wayne" <wmcmorrancharter.net>
Date: Tue, 19 Apr 2011 19:22:24 -0700
We inherited an Athena Computer like the one you show but the manuals indicate that it was built by Univac (A Univac representative also reported this.) We uses it for a number of years, after modifying it so we could do some more general purpose computing. Finally we traded it in as scrap metal.
Wayne McMorran, Professor Emeritus
Cal Poly State University
San Luis Obispo, CA 93407
I was in charge of the project and watched the pieces of the machine arrive in a flat bed truck. After several weeks of installing the false flooring, placing the cabinets in the proper places, connecting "plug x" to "socket x" we finally pushed the start button. It started right up and worked without flaw the entire time we had it. The one cabinet that was strictly missile launching hardware was used to make modifications to the machine.
We changed the useless "countdown register" into a makeshift index register, added A/D and D/A converters and, without air conditioning we refrained from using the machine on hot days. At one point, with the addition of an oscilloscope with a long persistence tube, I managed to make a somewhat crude graphics terminal. I used a genuine State of California ball point pen holder to hold the light sensing diode to point at the screen. Eventually we sold it as scrap metal (all the gold plated contacts and stainless steel hardware should have been worth something).
After we had the machine for several years, we finally obtained a complete set (10?) of manuals. Prior to that we had only one of the manuals but were able to glean enough information from it to meet our needs.
I noticed one article that showed the "Battle Short" button but the writer did not seem to know what it did. I finally found out when talking with one of the men who designed the Athena. He told me, "DON'T EVER PUSH THAT BUTTON!!!" It seems that about 5 seconds before lift-off, the operator pushed that button. What it did was to short out EVERY fuse and circuit breaker in the entire system. They would rather the computer have a melt down and get the missile off the ground than mess up a missile firing. We never pushed it!
I just realized that I had seen your courseware web site where you talked about the Athena.
Talking about the Athena brings back a lot of memories. In the early days of my career at Cal Poly, the Department head would come into my office an ask the question, "such-and-such" a bank wants to give us their old computer. The first question I'd ask was, "Does it have Vacuum tubes?" The answer was always, "Yes!" I would tell him, "Tell them thanks but no thanks!" It would take half the power from a local power plant to run it and the other half to run the necessary air conditioning.
I received the offer of the Athena from a former classmate who was working for the GSA (or some similar organization). We got everything except the ten instruction manuals. We did, through another source, obtain the really important one.
We also, eventually, got the safe opened. A student in one of our classes had worked for a locksmith for a time and was able to get at the lock through a hole into the tape storage compartment. It was empty!!
Someone probably took pictures of it, but I am not aware of any. We did have a Univac photo of it. It proved handy in trying to figure out where the many cabinets were to be located.
Control Console, Titan II ICBM 1963
This work is licensed under the Creative Commons Attribution-ShareAlike 3.0 License.
11:36, 17 November 2007
|From: "Vern" <garmcocox.net>
Date: Sun, 11 May 2008 15:46:06 -0700
Hope this gets to you. I just ran across the website www.silogic.com/athena.html and saw that it was just updated last month.
My name is Vern Gaman and I live in Las Vegas, NV.
When I got my BSEE degree from Iowa State University in 1961 my first job was as a field service engineer at Remington Rand Univac in St. Paul, MN. I spend from June through December in St. Paul going to school on the Athena and then working on the Athena factory test stands.
In January of 1962 I went to Denver and worked there until May working at the Titan sites on the old bombing range East of Denver. That May the Air Force took over the site and I was transfered to the Sperry Gyroscope division of Remington Rand to work on Polaris Submarine computers
Your web site and the pictures brought back a lot of memories. Thanks for preserving this stuff.
Isn't it amazing to compare the capabilities of the old Athena to the PC sitting on your desk now.
Las Vegas, NV
Subject: Re: Athena
Date: Mon, 12 May 2008 17:00:44 -0700
Thanks for the note.
First, no problem with my email on your website. Should be interesting to hear from other "Athena People".
Second, I've attached some thoughts about 1961 and the first part of 1962.
a senior EE student at Iowa State, I got my first taste of the computer
world. Iowa State built a copy of he U of Illinois Illiac computer and
it came on line in early 1961. They had to build an addition to the
building for it, and it had some interesting hardware. For RAM memory
they used 'Williams tubes'. Should be something on the web about them.
The senior EE students taking some of the logic courses ended up
writing some simple software to run on the 'Cyclone', the name chosen
for the ISU version of the ILLIAC.
That got me started in the computer world and I spent the next 35 years working with computers.
We moved to St. Paul in June of 1961 and I started the ATHENA school. The school was 3 months long and as I remember, there were 5 of us in the class. Covered all parts of the system in great detail. Down to the individual gate level in the processing and IO sections. Spend a lot of time on the control console and the tape unit. And went through the power system and all of its relay sequencing until I could visualize it my sleep.
Had an excellent instructor and I credit those 3 months with giving me a solid understanding of computer systems that helped throughout my career.
After the school, the other 4 students were shipped off to Titan I sites around the country. My wife and I were expecting our first child in late 1961 so the company kept me in St. Paul until after the baby was born.
I got sent to work on the Athena's factory test stands. As components came out of manufacturing a system was installed in one of several secure rooms. The school facility was in building south of the center of St. Paul, right on the river, while the manufacturing area was in the center of town I think on University.
I worked with several of the factory test techs in getting the new Athena up and running and ready to ship to a site. Don't remember any particular problems. This was getting toward the end of production and things were running smoothly.
Just before Christmas of 1961 we left St. Paul and went to our folks house in Iowa where I left my family and reported to the Univac office at the Buckly Air National Guard facility on the East side of Denver.
From January until early May I drove about 50 miles out onto the old bombing range east of Denver 5 or 6 days a week to one of the five Titan I complexes. I'm not sure when work started on those sites, but all of them were pretty well completed and all the equipment was in them when I got there.
When I went in to start my shift, I would fire up the Athena and run the diagnostics to make sure everything was ready for the days testing.
Most days were spent getting ready to run Air Force acceptance tests, and many test attempts were made.
The test that was required before acceptance included:
Getting the launch alert.
Fill the missiles with LOX. The kerosene was already on board.
Raise one of the missiles up on the elevator
Raise one of the radar antennas and lock on
Simulate a launch and run a simulated guidance program on the Athena
Raise a second missile on the elevator
Lower the first radar antenna and raise the second and lock on
Simulate a launch and run the guidance simulation,
Raise the third missile
Raise the first radar antenna again and lock on
Simulate the launch and run the guidance simulation.
This test was attempted at least once a week and sometimes several times in a week, but there was always something wrong.
The biggest problem was in the LOX fueling system. Typically the probes going into the birds tanks would freeze up and not retract.
I don't remember ever having a problem with the Westinghouse Radar or with the Athena. But most of the tests didn't make it to the point where we were involved.
When the tests were actually run the entire complex was sealed up. All of the blast doors were closed, we had parked a couple of miles away and hauled in on busses. I didn't think much about it at the time, but if they would have had a failure that caused the missile to fall (as I think one did at Vandenberg), it could have gotten interesting in the control center.
Finally one day in late April, 1962, the test was successful and the Air Force said "we'll take it". I'm glad that there was never a call for a real launch, I'm not sure it would have worked.
I was transferred in May to the Sperry Gyroscope Division of Remington Rand in Syosset, Long Island, New York, There I went to school for 3 months to learn about the Polaris Submarine navigation computer before going to the shipyard in Newport News, VA to work on new Polaris boat construction. But that's another story.
An interesting note though. After going through sea trials of the USS James Monroe, SSB(N) 622, I took a job in engineering with the AC Spark Plug Division of GM in Milwaukee, WI.
At AC I ended up working on the guidance computers for the Titan II ICBM and the Titan IIIC space launch vehicle. These computers were built by IBM in Owego, NY and were airborne units. They were about 2 feet square and a foot tall. Had a drum memory about the same capacity as the Athena's drum. But no ram. All of the intermediate data was stored on "revolver tracks" on the drum. That's where the accumulator was also. Programming was a nightmare. Look up 'revolvers' sometime.
|From: Chromehooves Flickytail <chromehooveshotmail.com>
Subject: Found another Athena photo
Date: Sat, 29 Aug 2009 22:49:54 -0700
While searching through my files for something completely unrelated, I found another picture of the Athena console-- rather a nice shot. Sadly it is not direct from a print but a photo-copy from a base history. This shot is almost certainly taken at Vandenberg AFB in CA where the Titan I had a test facility used for testing systems of the missile complex for integration etc. This is evident from the room seen in the shot as it is not a domed structure as it would have been at other operational sites.
As before, this shows the Athena tasked as the missile guidance computer set for the Titan I weapon system. I suspect the man in the foreground is a RRU engineer, or possibly with Bell Labs (the guidance software authors) or The Martin Co. going over the unit's use and function. Perhaps one of your group might be able to indentify him? Next to him is an AF missile guidance technician.
I will keep my eyes peeled for other shots. I have documents covering the Fortran and Besys code for both the Titan I guidance integration and simulation and missile guidance programs if you are interested. They are not completely scanned at this point but are in the works with many other Titan-related tasks.
|Date: Sun, 05 Aug 2007 22:27:55 -0700
From: walter silva <wlsilvasbcglobal.net>
Subject: Athena computer question.
I came across your website while searching google for any photos of the Athena guidance computer used in the old Titan 1 missile system. It is veeeeeery hard to find photos of the Athena, and I was wondering if you might possibly have any photos you could share from your days of working with this machine? I am interested in the early first generation missile systems, and the Athena computer used in Titan 1 is one of the neater parts of the control room. I enjoyed your website, and many thanks if you have anything Athena related you can share.
Thank you for the very nice reply, and many many thanks for being willing to share the photos you have of the Athena you worked on! Any shots that you can share would be fantastic, even if they are not great quality. There is soooooo little information or photos avaiable on the Athena, it will be a real treat to see the ones you have from school, and please take your time in scanning them, you are already doing me a great favor in just being willing to share them.
Have a great one. Walter
Great job on the Athena website!
There is so little info. available online covering the Athena, your website is a great addition and it is really fun to hear the stories of what happened to at least one of the former Titan 1 missile sites Athena's :) I wish I had material that I could share, but I have found it very very hard to dig up anything on the Athena, your photos you posted are by far the nicest I have seen yet. One website you might want to look at is:
This is a friend of mines website that gives a great photo tour of one of the Colorado Titan 1 missile sites he used to be the caretaker for. The link above will take you to the control room page, and he has some neat old photos of the Athena installed in the launch control center. Mark would you happen to have any other photos of the Athena control console? I am a nut for the really early computers and I would love to see any other pictures you might have. Thanks again for posting the Athena material, and I hope we chat again :)
|From: "walter silva" <wlsilvasbcglobal.net>
Subject: Athena computer in missile site
Date: Wed, 18 Aug 2010 01:58:35 -0700
Hope you are doing well, it has been a long time since we chated. I dont know if you remember, but I contacted you some time back before you had the Silogic website with questions about the Athena and the photos you had posted on the web, I think I may have helped nudge you into starting silogic up :)
I see the site has come quite a ways, and it is really looking great!
I found a great video clip of the Titan 1 guidance system I thought you would enjoy, the clip shows Athena being loaded with its targets, and the clip has some great shots of the Athena and its equipment.
Here is the link: http://www.criticalpast.com/video/65675072500_Command-Guidance-system_Titan-I-Missile_control-center_operation-room
Let me know how things are going, and thanks again for posting all the great information on Athena.
|Date: Sun, 26 Jun 2011 21:30:41 -0400 (EDT)
From: Dan Miller <danveraearthlink.net>
Subject: Athena II Computer
My name is Dan Miller I'm 71 You don't know me and never have. I live in Ohio. However I'm interested in your Athena project. I think I can help somewhat. I've been told that I have a keen memory, not quite photographic but close. I have some archival tech data if I can find it and a lot of first hand knowledge regarding my old friend.
I was surfing this afternoon so I thought I would see if there was anything on the net about my old friend Athena. Sure enough your Athena page popped up.
A little background. In 1960 I was assigned to Sheppard AFB to be an instructor of a newly developed computer system to be used as a guidance computer for the Titan I ICBM (Inter Continental Ballistic Missile). Instructors from Remington Rand Univac came from St. Paul, MN to teach instructors and the first Air Force combat crew stationed at Lowery AFB, CO. The course was to take 6 months. I graduated in Feb 1961 at the head of the class. The course consisted of total repair and programming.
From then, I along with several other instructors taught every AF combat team. I also assisted teaching the Guidance Control Officer Course. By 1965 those courses were completed and we were transferred to another Guidance System for PGM437 an anti-satellite missile program using the Control Data 924A computer which was what they called a second generation computer. Subsequently in 1966 I was transferred to Vandenberg AFB, CA to begin getting familiar with the Titan IIIB program. Along with training the Air Defense Command combat crews for PGM437. In 1966, I along with one other instructor and the first combat crew were sent to St. Paul, MN for 6 Months training for the UNIVAC 642B and UNIVAC 1219 computers.
I actually wound up teaching some of the system since Univac's instructor didn't understand the system.
Back in Vandenberg I continued to teach both the enlisted and officer crews for PGM437 till Sept 1967. I then transferred to Univ.of Arizona and graduated in Feb 1970 as a Mechanical Engineer. While I was at Arizona I was able to experience the power of the CDC 6600. Let me know if you would like any of the technical info I have stored away in the Grey matter.
Cheers, Dan Miller
PS. Sometimes this stuff still keeps me awake at night.
|Date: Tue, 19 Jul 2011 14:33:53 -0600
From: Harlan <harlan-bcomcast.net>
Subject: Athena compurer
I graduated from the University of Omaha in June, 1960, with a degree in Physics and Math. At age 15 I had become interested in electronics, was self-taught , and started doing electronic (radio, TV, etc) service. I ran my own service through high school and college, the business paying for a good part of my education. Upon graduation, I accepted a job with Remington Rand Univac, in St Paul, Minnesota, as a field engineer on the Athena. I attend classes daily from my arrival in St. Paul in June, 11960 until October, 1960. The school was in a building at the intersection of Mississippi River Drive and Ford Parkway. Across the street was Ford Motor Company's St. Paul assembly plant.
I was assigned to Cape Canaveral, where there were 2 Athena's. While the two were (almost) identical, the older one had been (mechanically designed to going into a semi trailer(s). It was logically identical to the other (newer) Athena (which appeared identical to the ones in your photos), the older one had the logic on pull-out drawers. And a control panel was built into a cabinet - there was no control console on that machine.
The newer Athena had an additional cabinet, with a "record" section. This consisted of an additional core memory, which was identical to the main 256 word core - except it was limited so that only 64 24-bit words could be stored. And it had a paper punch, which was the output device. It was my understanding that there were two Athena's with the record section: Cape Canaveral and Vandenberg AFB. This was so that after a guidance operation the data from that operation could be analyzed to see just how the guidance computer had performed.
The drum stored 17-bit words in parallel - an unusual arrangement for a magnetic drum. Timing for the Athena was derived from the drum: there were two timing tracks, a clock track, and a sync track. The timing track had a pulse written every 5 usec (microseconds) around the drum. The sync track had ONE pulse written, at word zero, to provide for resynchronization on the timing circuits, if necessary. Those 2 tracks didn't have any provision for writing - no write amplifiers were included for those heads. All other heads on the drum's shroud had write amplifiers - BUT the ONLY time those write amp's were enabled was when loading a program from paper tape. I mentioned above that the drum's word length was 17 bits. There were two instructions that accommodated 24 bit data words: a "load data left" and a "load data right" , which would load the respective 12-bit left and right halves of a 24-bit data word into the core memory.
The reason for a 24-bit data word is as follows: missile guidance is done in an earth-centered-coordinate system. Thus, the initial launch point has a "Z' coordinate initial position of (approximately) 20,000,000 feet (1/2 the Earth's diameter, or 4,000 miles, times 5280 feet per mile), or some 20 million feet. To get to 20 million you need a data word of 24 bits, assuming a desired accuracy down to a few feet. Some other computers that I am familiar with: the Librascope drum computer for the Atlas-Centaur deep space launch vehicle was a 25 bit machine; the Minuteman computer, which I think was from Autonetics, had a 27 bit data word, which could be divided into 3 "syllables", or 3 9-bit instructions. The Gemini 2-man spacecraft had an IBM-Owego computer, using multi-hole cores and glass delay lines, and was a 39-bit word, which could be either 3 syllables for 13-bit instructions, of one 26-bit data word and one 13 bit instruction word; and as I remember the Titan-II and Titan-III computers were from IBM-Owego drum machines, and were 2-syllable 24-bit data word machines.
Back to the Athena: each instruction had several steps. while I don't remember the exact sequence (it has only been 50 years since I last saw an Athena - how could I forget all these details so quickly), it went something like this (each step being 5 usec apart): step 1, load the contents of core location N to the accumulator; step 2 - load the contents on core location N+m to the quotient register; step 3 - add the contents of "A" and "Q". but the results in (some other register); step 4 -- go the drum address "track + word" for the next instruction; step 5 - store the results from this instruction to core location N+p. In other words, each instruction consisted of several "micro-steps". The logic levels in the Athena were: a logic zero was -2.0 volts, and a
logic one was zero volts.
A misstatements: one comment referred to the Westinghouse radar used in the Titan-I guidance system. It was actually a radar designed by Bell Telephone Labs, and manufactured by Western Electric, both firms, of course, being subsidiaries of AT&T. Another possible error has to do with the gas used in the Athena's logic modules - someone said it was Argon. My memory says it was dry nitrogen. In my time with Univac at Cape Canaveral, it got to be complete boredom. Nothing ever failed. We did have a set of modified logic modules - they had a switch added so
that a fault condition could be set in that module, that module used to replace a normal module, then let the guys find the fault and trace it down to the specific faulty module. (The switch was next to the 50-pin connector in the bottom of the module, so that it wasn't visible when everything was put together. The regular modules, needless to say, did not have the fault switch.)
I finally got so bored I went out and found another job - I went to work for General Dynamics/Astronautics on the Centaur, being responsible for the Librascope guidance computer - which was carried on the launch vehicle and worked in conjunction with a Honeywell 4-gimbal inertial platform. That program got involved in political problems, and both my lead engineer and I left for RCA in suburban Boston, on the SAINT - or satellite inspector program. I had been there for 6 months, and my first child had just been born, when the Secretary of Defense canceled the program. I and one other engineer were transferred to the RCA plant in New Jersey that built satellites. After a year there, I left for McDonnell Aircraft in St. Louis, and the Gemini program. We had the IBM computer and the Honeywell inertial platform. And I spent a fair amount of time in IBM's Owego, New York plant. After the NASA/Gemini program, the Air Force contracted to use the Gemini to go to and from an orbiting lab. And I was the project manager for the IBM components - computer and instrument panel items - an "incremental velocity indicator", used for rendezvous operations, and manual data insertion unit, and a manual data readout unit, used by the astronauts. While working on Gemini, I had the opportunity to meet several of the astronauts, including Alan Shepard, and Gus Grissom.
After Aerospace, I did some other things, including project management of supervisory control system for electric utilities. Now, I am retired. If anybody wants to discuss the old days of 40 or 50 years ago, e-mail me.
After I sent my previous message, a light went on in my head, and I realized a couple of things. With regard to the record section, I am quite sure that in addition to the high speed paper punch, it ALSO had a mag tape transport. It was, I believe, a six-level tape, recording 6 parallel channels. That is what was used for post-flight analysis.
While our primary purpose was guidance for the Titan-I, we also provided guidance for satellite and space launches, several a year, as I remember it. And when we would get a tape with the program for a satellite or space launch, it was ALWAYS on mylar - never on paper. I recall the mylar as being silvered on one side, and a dark blue color on the other side.
Also: at Cape Canaveral, we had two MG sets for each computer. For some reason, it was a 420 cps. This is non-standard - aircraft operate with 400 cycle, and (according to a friend was in the Navy) 400 is standard for ship. Our MG sets were powered by normal 60 cps utility power, EXCEPT when we were going to do a guidance operation. Then, the entire building switched to a standby diesel generator.
I do not have any information or literature about the Athena - I haven't had any contact with that item for 50 years. And yes, you certainly may use my e-mails as you see fit. Use then either as sent, or edited down, as you deem appropriate.
Final: the military designation for the Athena was AN/GSK-1.
Date: Sun, 4 Apr 2010 20:36:20 EDT
Subject: Re: Athena
My wife & I just got back from DC (cherry blossom time). Yesterday, we walked around the national mall a little and stopped in at the Smithsonian castle. I had to ask.
"Once something is accepted by the Smithsonian, do they ever throw anything away?"
I mentioned a main-frame computer donated in the early '70's. One woman at the information desk tried looking it up on her computer but without results. The elderly woman at the information desk told me that she had worked behind the scenes in the anthropology section for eight years and in that time she never saw anything thrown away. She made the statement twice and mentioned some large warehouses out by Andrews Air Force base. She also mentioned everything has to be in deep freeze because of insects. That may be true in anthropology, I'm not sure they would freeze technology.
Maybe, just maybe, the Athena is still there. There could be a place for the console to be on display:
Beyond the Limits -National Air and Space Museum Exhibition Home Page (http://www.nasm.si.edu/exhibitions/gal213/)
So, all that would be needed would be a modern power supply and a mini-computer to bring the old console to life. It would also be nice to agree on the message that would be encoded in the flashing of the lights.
"Never trust a computer you can pick up." - Pat Stakem
I was in on the donation and delivery of the Athena. It went to the Silver Hill Facility (which is what you were referring to) as far as I know, and was put into storage. Think: that scene at the end of "Raiders of the lost ark"
also helped with the donation. I spent most of my evenings that summer
('72) between graduation and the start of grad school recableing all
the interconnections between cabinets so the machine could be taken
apart for shipping without just cutting wires. Lots of soldering
and burnt fingers. I also helped them load it into the moving van
for its trip to the Smithsonian. I also at that time snuck in a couple
of B250's onto the van for good luck.
I was told that at one time that the main console had been on display with some history of computers exhibit at the Smithsonian. I didn't get to see that (I think, its vauge, maybe I did).
|From: Patrick Stakem <PStakemloyola.edu>
Date: Thu, 26 May 2011 14:44:03 -0400
The Smithsonian called me today. They are working on the Athena! They need some help. Let the guys know. WE ARE PUTTING THE ASDG BACK TOGETHER!
They have Bogart parts mixed in with the Athena stuff, and a lot of things they need identified.
contact is Peggy Kidwell, 202-633-3828, kidwellpsi.edu
Dr. M retired quite a few years ago.
Did they say why they were doing this or provide any more specifics? These days, museums (and the Smithsonian is one of them doing this) tend to use artifacts to tell stories rather than to just display the artifact as some neat old thing. What story are they trying to tell? I can't believe they would want to tell a story of how a bunch of college kids took an old cast of computer and restored and enhanced it :-) I can only imagine that they are trying to tell a story about the early ICBM defense (from where are they going to get the Titan I :-) I think the Titan I / Athena was the first silo ICBM. Is the display to be associated with some "larger" story and if so what part is it to play? Or something completely different. Inquiring minds want to know ;-)
73, Chris Hausler
|From: "Mark DiVecchio" <markdsilogic.com>
Date: Fri, 27 May 2011 17:04:41 -0700
Subject: Athena Computer
I just got an email from Pat Stakem. He said that you contacted him about the Athena Computer. He didn't give many details about the help you need so I thought I would send you this email.
We have an informal mailing list of about a dozen former students from Carnegie-Mellon University who worked on this computer.
If you tell us what you need, we might be able to help out.
|From: "Kidwell, Peggy" <kidwellpsi.edu>
To: "'Mark DiVecchio'" <markdsilogic.com>, Patrick Stakem <PStakemloyola.edu>
Date: Tue, 31 May 2011 08:09:38 -0400
Subject: Athena Computer
Dear Pat and Mark:
Thank you for your offers of help relating to the Athena computer. Many years ago, several people from Carnegie Mellon (including Pat) brought to the museum considerable parts of the Athena and related components. There were complicated questions about ownership of the machine, which delayed routine processing of it for many years. Some sorting has taken place, and I am now trying to actually complete the processing. I hope to go and look at the pieces stored off-site next month.
There are numerous small modules which an intern began looking at this spring. Most of these are clearly associated with the Athena, or with a Ferranti paper tape reader that came with it. However, mysteries remain.
My plan is to compile a list of the pieces and to obtain rough photographs of the mysteries. Would you be willing to look at these, identify what you can, and should you not know what they are, circulate the images on Mark's web site for identification? It is quite fascinating to see how the Athena was used - and modified - in a university setting.
Once again, thank you for your attention.
We would be happy to help you out doing the indentification of the pieces that you have. If you send me the questions and any photos, I can circulate the photos via my web page and I'm SURE that we can tell you what is what.
Many of us spent years with the Athena and have a special fondness for it. The Athena provided us poor undergrad engineering students a venue to actually wire up real computer circuitry that did real operations and not just a lab experiment. I think that Pat Stakem had real forsight to have arranged to have CMU donate the Athena to the Smithsonian Institution back in the early 1970's.
If you need to call me, my phone is 858-245-6427
|From: "David Chou" <dchouuw.edu>
Subject: Atlas Agena lauch computer display
Date: Thu, 28 Nov 2013 13:57:08 -0800
This Atlas Agena launch computer was on display at the Smithsonian Air and Space Museum in Virginia where I visited last week. I don't know if this was the display for which the Smithsonian was soliciting assistance, but looks a lot nicer than the old resurrected computers at Carnegie.
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