What was the first computer used for IC testing in the 1970s?

[dlgoff]

TL;DR Summary

The first computer that I played with

When I worked for Kantronics, Inc back in the '70s, this was the first computer, the DEC PDP 8, I used to do IC testing after hot & cold temperature soaking, the engineer that could program it with his eyes closed, now works for NASA:

 

[jedishrfu]

A most magical computer! The Altair 8800 and Altair 6800 were pale imitations.

 

[hutchphd]

Summary:: The first computer that I played with

after hot & cold temperature soaking, the engineer that could program it with his eyes closed

That is what stuck after my firsr read...

I remember those but never used one.

 

[dlgoff]

That is what stuck after my firsr read...

I remember those but never used one.

When I was involved with it, we had 50K ICs to test. Needless to say, it took a long time. The guy who works for NASA (I assume he still does; haven't heard from him for years now) could enter data and addresses faster than I could type on a typewriter.

 

[Baluncore]

That appears to be a slow, and low-power PDP-8/S.
If I remember correctly from the 1970s, it had a 1 bit serial CPU, and was used portable, in the back of a truck for seismic surveys.

 

[Borg]

I looked at that and it reminded me how computers used to have a key for security.

 

[Mark44]

The PDP-8 was before my time as far as programming goes, but I do recall reading about it. Nowadays, we tend to think that bytes are and always were 8 bits, and don't realize that in the early days this wasn't always so. The PDP-8 architecture used 12-bit words, so a half-word (or byte) would have been 6 bits.

This was a very simple computer, with only three registers: AC (accumulator), PC (program counter), and L (link register/status flags). Quite different from present day computers.

Wiki article: https://en.wikipedia.org/wiki/PDP-8...es at different points in the operating cycle.

 

[dlgoff]

The PDP-8 was before my time as far as programming goes, but I do recall reading about it. Nowadays, we tend to think that bytes are and always were 8 bits, and don't realize that in the early days this wasn't always so. The PDP-8 architecture used 12-bit words, so a half-word (or byte) would have been 6 bits.

This was a very simple computer, with only three registers: AC (accumulator), PC (program counter), and L (link register/status flags). Quite different from present day computers.

Wiki article: https://en.wikipedia.org/wiki/PDP-8#:~:text=The electronics of a basic PDP-8 CPU has,purposes at different points in the operating cycle.

Yes 12 --bit words seems strange now days. Thank you for the wikipedia link.

 

[jedishrfu]

GE / Honeywell machines in contrast used 36 bit words.

 

[anorlunda]

GE / Honeywell machines in contrast used 36 bit words.

Not all of them. The GEPAC 4010 and 4020 process computers had 24 bit words. I think you're thinking of the GE 625.

24 bits was nice. 8 octal digits.

 

[jedishrfu]

Yes, the GE625. GE635, Honeywell 6000 mainframe machines were the 36-bit ones.

 

[Baluncore]

24 bits was nice. 8 octal digits.

I think you mean 10 octal digits.
Because the first person to say "eight" paid for the drinks.

 

[Mark44]

I think you mean 10 octal digits.

Ha ha!
Sort of akin to "there are 10 kinds of people: those who understand binary, and those who don't."

 

[jtbell]

Yes, the GE625. GE635, Honeywell 6000 mainframe machines were the 36-bit ones.

The DEC PDP-10 also used 36-bit words.

When the U of Michigan physics department retired its PDP-10 and switched to a VAX 11/780 (32 bits) in the late 1970s, I had to write a program (in Fortran!) to convert my research group's data tapes. I had to get down "in the weeds" with the details of integer and floating-point numeric formats on both machines.

 

[Baluncore]

In the early 1970s, the Burroughs large systems were very advanced for their time.
They were stack based, with 51 bit wide virtual memory, but the users only had access to 48 bits of the data, and no access to the address. The OS had access to the 3 tag bits that identified memory use which made the system very secure.
https://en.wikipedia.org/wiki/Burroughs_large_systems

 

[jedishrfu]

with respect to the Burroughs there was a story I heard from our school where an engineer / programmer from Burroughs was taking classes and managed to get his hacker program running.

I think it played Anchors Aweigh on the printer and then started shutting down subsystems one by one freaking out the computer operators on duty. I never found out if the guy graduated or not after a stunt like that. I also suspect that he brought in the program from work and didn’t write it himself. It may be also that this is just an urban legend from my school.

 

[anorlunda]

I think you mean 10 octal digits.
Because the first person to say "eight" paid for the drinks.

Ha ha. Zing. You caught me flat footed.

Some people might be unaware of BCD decimal computers. Notably, the IBM 1401 (business) and IBM 1620 (scientific), both highly successful computers of their time.

The 1620 was said to be, "variable-word-length decimal, as opposed to fixed-word-length pure binary." It used lookup tables for addition, subtraction, and multiplication, and software subroutines for division. My first exposure to computers was on a 1620 in the year 1962. It used punched card input and punched card output. Printing was done by a separate free-standing device. Freshmen students were told to use FORTRAN. Only advanced students got to write machine code.

 

[dlgoff]

(in Fortran!)

I really loved Fortran. When I used it, we had to turn in decks of cards for a program and wait for hours to get the output printout in order to trouble shoot the errors. I also have memories of an EE project where we were given a deck of cards that were all out of order. The assignment was to get them back in the right order.

 

[jtbell]

During our "PDP-10 era", most of our programs were on punched cards. After we switched to the VAX, everybody was "encouraged" away from punching cards on a keypunch machine, and towards keeping source code on the computer and editing it with the newfangled video terminals. ASCII text only, of course. I became something of a whiz with the TECO text editor.

Terminals that could also display line graphics didn't come until later. During my last year or two in grad school (early 1980s), I programmed one of those (still in Fortran!) to graphically display particle tracks through our detector.

 

[jedishrfu]

I think Tektronix had terminals where real line graphics could be done. Basically green lines on a black background, no color.

 

[dlgoff]

I think Tektronix had terminals where real line graphics could be done. Basically green lines on a black background, no color.

Yes. I remember working on those terminals.

 

[jedishrfu]

We used them at GE to draw telco maps as part of the GE US DIalcom network. Each line represented a telpack, a licensing agreement where N simultaneous calls could be made from city to city.

GE would structure calls such that they conformed to the telpacks in use so as not to be overcharged for overuse. As an example, a call from NYC to Boston might exceed the telpack limit at that time so it would be rerouted NYC to Schenectady and then Schenectady to Boston.

At least that was my understanding at the time.

and the dissolution of 1981 Telpack pricing:

https://www.nytimes.com/1981/05/07/business/company-news-telpak-discount-ended-by-bell.html

 

[phyzguy]

I remember we had one of those PDP-8s when I was in school. One time we needed to re-boot it. First you had to enter a set of instructions using those white and orange binary switches on the front. After you had entered maybe 50 combinations (hard to do without making a mistake), this basically installed a simple program that could read a paper tape in the tape reader. Then you read in a long paper tape, which took at least an hour. That basically installed the OS, and you could begin programming it. Those were the days!

 

[Nugatory]

Ha ha!
Sort of akin to "there are 10 kinds of people: those who understand binary, and those who don't."

Mmmmm... No. The 10 kinds of people are those who understand ternary, those who don't, and those who think this a joke about binary.

 

[DaveE]

IMSAI 8080 was my first hands-on computer.

I was in high school. No other devices, no I/O, no storage. So your program was entered into RAM with the front panel switches and disappeared when the power was turned off. You got your output by reading data from RAM locations. No compilers, assemblers, linkers, etc. The UI was access to the data and address buss with LEDS for each. I recall being really, really, good at flipping those switches. OTOH, it was such a PIA that I think my crowning achievement was to write a program to multiply 8-bit numbers.

It was a great introduction to HW, but an awful way to learn programming.

 

[jedishrfu]

No kidding. I had the MITS Altair 6800 and it had the same input method and lack of peripherals. You could buy them but the cost was simply astronomical.

I considered buying a CRT terminal. The cheapest was the Televideo 910 terminal. It was white chars on a black screen and gave you a headache from the CRT hum. I used them at work but preferred the much cooler Televideo 925 but it was too expensive.

The plan was to connect the terminal up to the Altair and use the machines monitor program to enter and run programs. But I decided against it when I heard about the Radio Shack TRS-80 coming to market and felt it was more what I was looking for.

 

[happyhacker]

Summary:: The first computer that I played with

When I worked for Kantronics, Inc back in the '70s, this was the first computer, the DEC PDP 8, I used to do IC testing after hot & cold temperature soaking, the engineer that could program it with his eyes closed, now works for NASA:
View attachment 294005

I worked for BT back in the early seventies with the first broadband (2MB PCM switch) run on a PDP11 doing the call handling. Stored Program Control they called it although that sounds a bit weird now. It wasn't long after that the microprocessors came in with MSI. What processor did the PDP have?

 

[hutchphd]

Don't know where else to advertise this very interesting (to me at least) interview that only a geek or proto-geek would love.

Brian Kernighan interviews Ken Thompson​

 

[Mark44]

When I worked for Kantronics, Inc back in the '70s, this was the first computer, the DEC PDP 8, I used to do IC testing after hot & cold temperature soaking,

The first computer I worked with was in '71 for a programming class I took at my first college. I have no idea who manufactured the computer, as all I did was keypunch a deck of cards (in PL-C, a Fortran-ish language), and submit them between a few Job Control Langauge (JCL) cards. Since programming was something I knew very little about, my programs usually didn't compile, and I would get back about 6 feet of fanfold paper with gibberish covering most of it. Eventually I got the hang of things, and my programs would run and produce reasonable results. I didn't get the programming bug at the time, because it was usually a 24-hour turnaround between turning the card deck in and finding out whether the program ran or not.

My first exposure to computers was on a 1620 in the year 1962. It used punched card input and punched card output. Printing was done by a separate free-standing device. Freshmen students were told to use FORTRAN. Only advanced students got to write machine code.

That was pretty much my experience in two of the first three programming classes I took, in 1971 (PL-C with cards), 1976 (some flavor of BASIC on IBM 370?), and 1980 (Fortran 77 on ?? with cards). The next class I took was an advanced class in Fortran in '82, and the school (Univ. of Wash.) had switched over to VAX minicomputers running VMS. I dropped that class because the instructor admitted that he didn't know Fortran, and he wasn't familiar with VAX VMS.

@anorlunda, your early intro to computers reminds me of the sister of a close friend of mine. She got her PhD in Mathematics, but paid for it by her expertise with computers and programming in the 60s. She (Evi Nemeth) went on to write a very well received book on Unix System Administration. Sadly, both my friend and his sister have passed on - he died of cancer and she was lost at sea somewhere in the Pacific Ocean.

 

[dlgoff]

The first computer I worked with was in '71 for a programming class I took at my first college. I have no idea who manufactured the computer, as all I did was keypunch a deck of cards (in PL-C, a Fortran-ish language), and submit them between a few Job Control Langauge (JCL) cards. Since programming was something I knew very little about, my programs usually didn't compile, and I would get back about 6 feet of fanfold paper with gibberish covering most of it. Eventually I got the hang of things, and my programs would run and produce reasonable results. I didn't get the programming bug at the time, because it was usually a 24-hour turnaround between turning the card deck in and finding out whether the program ran or not.

This is exactly how it was for me as well. I remember sleeping in a waiting area waiting for the output. Then troubleshooting the code, punching more cards and turning the deck back into rerun.

 

[Mark44]

The first computer I worked with was in '71 for a programming class I took at my first college.

After thinking about this a bit, it was actually the fifth college I attended...
I eventually got my degree from that one.

 

[jedishrfu]

When i did one pgm at college in 1970 and saw the battle for the keypunch and the interminable wait. I decided to forego computers and just focus on my physics and math.

I did get an adding machine to help with physics labs ie working with logarithms for greater precision and sliderules for estimates.

As an Explorer Scout in Highschool, we did batch programming in Fortran on GE-635 machines. In a 90 minute class, I was able to get in two or more runs where others got only one because I’d get there early and one of the teachers would get it submitted and retrieve the printout immediately for me.

I owed him a great debt and would always help him with various computing tasks when I started working at the computer center and he was the supervisor in charge of all shifts.

 

[Shane Kennedy]

Summary:: The first computer that I played with

When I worked for Kantronics, Inc back in the '70s, this was the first computer, the DEC PDP 8, I used to do IC testing after hot & cold temperature soaking, the engineer that could program it with his eyes closed, now works for NASA:
View attachment 294005

It was the controller for a GenRad (1795?) functional tester. We also used DataGeneral Nova and PDP11/23 computers for system test.

 

[anorlunda]

Did anyone else ever experience the Interdata Model 1 computer? It had something in my opinion that was the dumbest thing ever on a computer -- a twist knob for speed.

The idea of the knob was to be able to slow the cycle time down enough so that you could follow the program execution in binary on the front panel lights. That was a debugging technique.

But psychology is far more powerful. Each and every programmer felt that the slow speed of their program was not because of their programming, but rather that the speed knob was not turned up fully. Therefore, every Interdata Model 1 that I saw had its speed knob twisted off and broken.

 

[George Jones]

I really loved Fortran. When I used it, we had to turn in decks of cards for a program and wait for hours to get the output printout in order to trouble shoot the errors.

That's nothing ; I had to wait at least 3 days per run! Part of my communications pathway was literally a bus. I have posted the following story before.

Fortran was my first programming language, which I learned in two high school computer science courses in grades 11 and 12 from 1976 - 78. My high school teacher was a CS grad from the University of Waterloo, so we did some good stuff, e.g., introductory numerical methods.

Running programs was quite an experience. "Back in the day", my small town high school didn't have computers. We penciled in bubbles on computer cards, and then sent out our cards by Geyhound bus to the nearest university, which would run our programs and send the cards and hard-copy results back by bus. Each program had an effective run-time of three or four days! After three days, you would find out that your program hadn't even run, because you penciled in a wrong bubble, causing a fatal syntax error. Result "Execution suppressed."!

Our teacher, Mr. Fennell, managed things well, making sure that we were working on multiple projects and getting results back every day. A very positive experience for (the then young) me.

 

[dlgoff]

Fortran was my first programming language, which I learned in two high school computer science courses in grades 11 and 12 from 1976 - 78. My high school teacher was a CS grad from the University of Waterloo, so we did some good stuff, e.g., introductory numerical methods.

bold by me (thought this was fun stuff).

I wish my high school would have had computer courses. I only was able to learn Fortran when in college.

 

[Astronuc]

I don't know the first computer I used, because it was accessed via a teletype and telephone modem. It was 1969, and the class was being introduced to BASIC. I later learned FORTRAN, PLC, APL, Pascal during the 1970s. FORTRAN was mostly done with punch cards on time-shared systems at the university (IBM or Sperry). APL was done on a video terminal (and I think tape), and I think PLC was also. FORTRAN was mostly what I used through undergrad and grad school, and professionally. I still use legacy code written in FORTRAN, although much of it has been upgraded to modern versions. I've had experience with C++, which I dislike.

At the second university, undergrad engineering students shared resources with science students, all using the computer science mainframes (IBMs). The Engineering School then (1980s) decided to get its own computing system, which started as DEC VAX-11/750 and got upgraded to VAX8650/8800 cluster (I used some pre-internet connections to run remotely on computers at NASA-MSC). During the 1980s, each engineering and science department received PCs and workstations, and we built our own networks. Computing systems have gotten more elaborate since, but I haven't kept up.

 

[hutchphd]

When i did one pgm at college in 1970 and saw the battle for the keypunch and the interminable wait. I decided to forego computers and just focus on my physics and math.

YES. I remember one evening (probably 1971) being at the computer center trying to get my FORTRAN program to run when I had an epiphany. Looking around me at the disheveled and forlorn souls hopelessly and repeatedly feeding decks of cards to the holy computer operator, I realized that these machines worked only by sucking the mental energy from all sentient beings nearby, and I treated them accordingly from that point forward .
I didn't really enjoy computing again until I got a commodore 64 and took a fancy to writing 6502 (6510) machine code. I think my lunar lander program (with real time out-the-window views) was pretty good. Truth be told it was the last computer I really knew everything about and I enjoyed that very much.

 

[jedishrfu]

@hutchphd I too had a similar epiphany though it was with the Altair 680 then the TRS-80 and then the Commodore 64. I liked the VIC-20 but it was just too limiting. I really liked the Atari 800 but it was too pricey being just married and having no cash.

I remember that there was a sales event where Commodore would give you a $100 off a Commodore 64 if you traded in a game. A coworker suggested a cheap $10 pong game from Kaybee Toys.

At the time, I decided to buy a 64 just before the trade-in expired Commodore dropped the price a $100 and still honored the trade-in so I effectively got the machine for $200 less at around $199.

With it color and ease of use, I just loved playing with the sprites which were so much easier to program than the Atari 800 machine player-missile graphics. The nearest you can get to that feeling of programming freedom now is the Processing IDE where with a few lines of code you can write a simple drawing program.

 

[pbuk]

Truth be told it was the last computer I really knew everything about and I enjoyed that very much.

The Commodore 64 and its contemporaries were the last generation of (general purpose) computers that anyone knew everything about. The complexity of every level of a modern system, from pipelined, branch predicting CPU cores, through multi-level caches to optimising compilers and language runtimes with automatic garbage collection it is simply not feasible to comprehend the state of any non-trivial system at any given moment.

 

[Mark44]

The Commodore 64 and its contemporaries were the last generation of (general purpose) computers that anyone knew everything about. The complexity of every level of a modern system, from pipelined, branch predicting CPU cores, through multi-level caches to optimising compilers and language runtimes with automatic garbage collection it is simply not feasible to comprehend the state of any non-trivial system at any given moment.

In a recent thread another member asked these questions (https://www.physicsforums.com/threa...-software-from-the-hardware-activity.1008862/):

Suppose one knows well the laws of physics but knows nothing about computers and IT. Would one be able to deduce how a computer works only by studying its hardware? Could one rebuild the software code and understand its meaning only by looking at the internal flow of bits in its CPU?

For the reasons listed by @pbuk, my thought was that these tasks would be difficult at best, and maybe impossible.

 

[anorlunda]

For the reasons listed by @pbuk, my thought was that these tasks would be difficult at best, and maybe impossible.

I think that's too discouraging. It depends on what you mean by "a computer". Many young people today could follow those Ben Eater videos to make a functioning computer on their desk, program it, and watch the results. The impossible part comes when you say "a computer" means a modern PC or equivalent.

Students still take Economics 101, even though nobody is capable of really understanding everything about a national economy. I think it's sad when the educators tell us that there's no room in the curriculum for a Computers 101 course, taking 3 months to build a computer and to write a "hello world" program.

 

[Mark44]

I think that's too discouraging. It depends on what you mean by "a computer".

The context for @pbuk and me was computers after C64 and presumably to include computers after 8086/8 to 80286 PCs.

Many young people today could follow those Ben Eater videos to make a functioning computer on their desk

Sure, but as I recall he was using a 6502 processor, which is similar to the CPU in the Commodores (Vic 20 and C64). In the thread I quoted, the premise was someone who knew nothing about computers, but did know the laws of physics. With the stipulation that "a computer" means something produced in this century, I stand by my remarks.

 

[Astronuc]

I think that's too discouraging. It depends on what you mean by "a computer". Many young people today could follow those Ben Eater videos to make a functioning computer on their desk, program it, and watch the results. The impossible part comes when you say "a computer" means a modern PC or equivalent.

Mark44's assessment is reasonable, and I agree. Even with a good knowledge of physics, it would be difficult to know how a computer chip actually works without some specialized education.

I remember vividly the time (~1977/1978), when the physics department at a university was desperately searching for someone to program a microprocessor, grad or undergrad. Anyone capable would have received full tuition and expenses from the department. I never followed up, but I suspect some CompSci/CompEng/EE students came to the rescue.

I had been exposed to how microcircuits worked and TTL, but I didn't find it as interesting as other topic related to radiation, astrophysics and particle physics, on top of all the other stuff I had to learn.

Thinking back, the first computer I had was a pencil and sheet of paper, followed later by a K+E slide rule (supplementing the pencil and paper), then an SR-51 calculator. The unidentified computer accessed though a teletype came between the paper and slide rule.

 

[dlgoff]

a K+E slide rule, SR-51 calculator

I still have both of these. At one time I posted photos of these (must have been many years ago though)

 

[Astronuc]

I still have both of these. At one time I posted photos of these (must have been many years ago though)

A classmate in 11th grade had an SR-10, and then upgraded to an SR-11 in 12th grade. He used to do physics and chemistry problems to 6 or more decimal places, while the rest of us used slide rules. Between 11th and 12th grade, I encountered my first HP-35. At some point, I purchased an SR-51. After I received my bachelor's degree, I received a TI-58C. Then later I purchased an HP-41CX, which I still have and use almost every day. Someone dumped an HP-41CX at work, so I snagged that one, too. So I have two.

 

[dlgoff]

IMSAI 8080 was my first hands-on computer.

I bought one of those in Topeka, Kansas when they first came out. Don't know what ever happened to it though.

 

[dlgoff]

@Astronuc

I found the post showing my old slide rules, etc:
https://www.physicsforums.com/threads/my-old-computer-collection.727751/post-4774103

 

[Quester]

HP 2100S:

 

[bob012345]

My how you all are dating yourselves! Well my first computer experience was also in the early 70's using punch card machines for class. I remember the feel and sounds in my head very well. I always loved the smoothness and clicking of the mechanical operation of the machine when making cards. In the mid 70's in grad school those machines gave way to terminals and Vax computers in awesome high tech rooms with raised floors and many large tape drives sorting out data from high energy particle experiments.

I missed the era of general slide rules by just a bit but I did use a round flight computer when I learned how to fly.