Running A PDP-8 From 1965 

I was a graduate student in Electrical Engineering at North Carolina State University when the department obtained a PDP-8, This was the first "personal computer" on campus and it was my responsibility. This was before there was a Computer Science department on NC State. I developed some demonstrations / lab exercise around it for EE students. I also used it to simulate a learning machine for my dissertation. Found Memories.

I cut my teeth in programming a PDP-8 in 1967. Our high school was the only school in Ottawa, Ontario to have its own computer then. It was completely refurbished by an electronics teacher then, Mr Weik, who had worked on the famous Avro Arrow fighter jet before it was cancelled and scrapped. I was one of the then few computer hackers at that school. We used lots of paper tape as the storage medium. It was a blast.

Spent many hours with a fellow grad student, Paul, working on one of these in the latter part of the 60's. We were using it as a graphics front end controller attached to a PDP-10. One day Paul yelled: "Hey it's on fire!" Sure enough, there was an evident candle flame behind the plastic front panel. We pulled it open. A carbon resistor near the key switch had decided to burn out spectacularly. It didn't last long. Service man replaced it and all was good again.

Early computer goodness - I have a magnetic core memory plane from a Russian PDP-11 clone in my technology tchotchke display case. I am older than the PDP-8 but some days my memory core plane seems to be less than 4K.

Ah! the "straight Eight"..!! I had one in my patch at Milan Polytechnic University.. As a DEC FS Engineer in the early 70's, it was my duty to do monthly PMs (Preventive Maintenance - sometimes Provocative ) where lots of fans and console filament light were replaced.. Also got to upgrade the memory from 4k (not bytes but 12-bit words) to 8K. Easy right? Not so, I add a bunch of red single height boards (the logic) another bunch of green board (the analog stuff) and the actual 4k core stack.. Plug and Play? not so, get out my Tek 465 scope with a current probe, run the memory diagnostic (paper tape loaded from the console Teletype) and watched this particular signal waveform (Inhibit current?) shape and amplitude while adjusting a little pot on one of the green boards. I remember taking me a while as I really didn't know what I was doing, but I did it! Such fun! I have really fond memories of all those "eights, -I, -L, -S and finally PDP8-A which earned me a whole week training in Paris, thankyou DEC!! lm

I've got a PDP-8E down in my garage, probably a couple of boxes of parts and a set of manuals, too.

You literally can't create enough of these videos. These are the coolest freaking videos on RU-vid!

An interesting aspect of the PDP-8 12-bit architecture is that it was implemented in an early microprocessor - the Intersil 6100 of 1975 (and later made by Harris). This was also implemented in low power CMOS making it the first low power microprocessor. At about the same time the RCA 1802 (COSMAC) came out and, for a while, these two were the only low power general purpose ones available. I designed a low power data logger as part of a system and had only the 6100 or 1802 to choose from. I opted for the 1802 with its pretty unusual architecture compared to most other processors. And some of its features appealed to me. Also, the OTHER manufacturers of microprocessors kept saying, "We will have a low power version next quarter." But they didn't. Quarter after quarter went by and turned into years. So, used the 1802 for a long time and then after other low power alternatives were on the market for a couple of years, did another comparison and switched to the 8051 family (and was very happy with it).

Before it went under, the Computer Museum, in Boston, sold those "flip-chips," loosely, in their gift shop. But it wasn't until later years that I took interest in what they were actually used for. Back then, they were just a cool novelty.

Gives me warm fuzzies to see the vintage computers still welcoming people to our labs, wish it was in mine. 😀

I love this! My introduction to Octal arithmetic was on a PDP-8e. Fun toggling in the boot loader to give it enough smarts to read the tape reader.

The music program was one of the first things I did when I had a Mark-8 microcomputer. Except I did input from a "keyboard" from a row of momentary contact micro switches. 1st version used single bit output to a speaker through a capacitor. 2nd version justed used the emitted RFI into any nearby AM radio. I only had front panel switches to input programs (in binary). Later I built an Octal keypad and display for faster programming. Good memories.

Many TTs had an attached paper puncher/reader. My first ever DEC BASIC programs were stored on paper tape for convenience (short progs). Super 'puter, the ultimate "blinkenlights" m/c which didn't need it's own apartment & associated 3-phase a/c

I was a long time employee for DEC, right up until they were bought out by Compaq computer as their business declined. I have two PDP 8F cpus and a whole mess of other stuff that were my "personal computers" in the 1980's before the IBM PC and the clones dominated the landscape. Thanks for posting the link to the Vintage Computer Federation. Perhaps they will be interested in a donation of my HW. I'd hate to simply toss it in the trash.

Many years ago, when I was a computer tech, I used to maintain a PDP-8i, among several other computers. Also, I got started in the telecom business as a bench technician overhauling Teletype machines, such as the M33 connected to that computer.

I'm glad there are people out there keeping these old computers alive...sort of expected the computer to play " Daisy"..

Very nice vid, thank your for posting it 🙂 In 1975, as a teen, worked at a company that had a DEC 8E or 8I (eye) ... I'm not sure which. Everything was paper-tape in, paper-tape out. No monitors of any kind. The TTY was only for boot-up and shutdown (at leas as far as I was told, remember, I'm just a kid at this point). Later we had a DG Nova II, with 16K of core memory. Young people probably can't believe you could run a system with four VDTs (Video Display Terminals) a paper tape reader, a paper tape punch, 50MB Trident T-50 disc drive, and a mag tape drive in so little memory.

Nostalgic video! The Russian-made clone of the PDP-8 was the first "personal" computer I was working with. Great video Fran! Thank you!

I’ve got an old PDP-11 that needs restoration. This kinda encourages me.

Back on the mid 90’s I worked in London for a company named AL Downloading Services. Man… you would have loved it there. Wall to wall old kit that nobody else still maintained. A lot of fun was had and they made a ton of folding matter. 🤓

This is awesome. Love the radio "output"! 😆I got to watch a CDC-3800 doing an orbit prediction run back in the day. The most sci-fi console ever had a volume control where you could listen to the processing take place. The orbit analysts pointed out when the noises would change to indicate that prediction was done, data was being stored, etc. Pretty crazy!

Gosh, I miss the old days. Computing is nothing like it used to be -- although there are probably a lot of folk who'd say "thank goodness" 😀

I got my first computer in the 80's (a TRS-80 with 4K of RAM) and I had a program that used the same radio frequencies as this demo. And it played the Flight of the Bumblees! I thought it was magical!

The company I worked at used them for sawmill setworks in the 70 & 80 4k core memory, paper tape readers for programing. still have the tapes

4K of RAM to hold everything, which in those days was one program at a time. To think that for the last two decades at least, most modern operating systems load executables into memory with the first 4K all zeros. It's defense against null pointers being de-referenced, to cause a segfault and keep critical data from harm.

Awesome, first computer I programmed on was a PDP-11.

very cool Fran!

Ah, the memories! Real deal hard core stuff. RESISTORS? That's a damn nice backronym.

I'm tempted to build a PDP8 (11, maybe?) case for my next computer. Pity that clicking the 👍🏻 button harder does nothing.

I worked for Control Data in the late 60's. We had 2 General Radio logic testers that used a PDP-8 to load the various tests. To boot up in the morning, you had to manually toggle in a RIM (Read in Memory) loader program before it would read the paper tape to load the program to test a particular pcb. If you made an error in toggling in the RIM, you had to start all over. It wasn't uncommon to take 10 minutes or more just to get it running a program.

Thank you for sharing this Fran! I have a bad habit of forgetting to record these tours when visiting museums and the information is often unique and fascinating.

Oh yes my favorite PDP system! I grew up with a PDP 11 in the basement, I don't think I saw the light of the Sun for close to 3 years! At least my mom knew where I was at all times...

The first computer I had my hands on was an HP 1134 with its 4K of core memory. It had its own high speed paper tape reader. Beside the computer was an ASR-33 with its paper tape reader and punch just like the one in this video. I still love the sound of a teletype rattling away when it is printing out a progam listing.

8:00 Entering the start code on the switches on the front of a computer ... Oh, how I remember doing that. 100032, stop, reset, program load ... boot from the hard drive, 100022 was boot from mag tape ... I was told the leading "1" was for "high speed" devices only. I remember the first time I saw a computer WITHOUT dip switches on the front, and I just couldn't imagine how that could be useful, a PDP 11/34 I believe it was.

I worked on a PDP-8 at Argonne National Laboratory in 1974. I was a sophomore in college, working for one of my professors over the summer. Then, in 1976, I worked on an HP2116 data acquisition minicomputer at Argonne, which was a much nicer piece of equipment. And in 1978, I did my Master's working on a DEC PDP-11/45, which was nicer yet. Thanks for doing these, Fran!

Thank you, thank you, this is so fun

When I was in high school, our math department leased a PDP-8. It had 4k RAM, no core. That was 1972 and 1973. The program to load the teletype driver had to be manually loaded using the switches. Then the Basic interpreter could be loaded from the paper tape reader on the teletype. The trig functions had to be deleted to have enough space to store a program. When I went to college, they had a CDC 3300 which used cards. You had to be an upper-classman to use a teletype.

Loving this footage from VCF - thanks Fran! ❤

Just casually playing the mother of all demos in the background

I remember one from college days cool electronic lab main college computer pdp 11

The comparison to a bouncing ball makes the inspiration for pong seem inevitable

Very cool! Thanks for sharing! Loved the history lessons and bonus tunes with my morning coffee!

What a wonderful video! I cut my teeth on a PDP-11, so this was great to see!

Very modern minicomputer, no tubes.

Wow I recognize that blue triad printer! The auto parts store I worked at had a triad point of sale system, we had 3 of those printers, plus the terminals and server along with a “lasercat” parts catalog lookup computer. This was in operation at our location from the 80s till 2013. I have never seen any triad branded computer equipment outside of that store besides very few RU-vid videos. Did they have a whole system or just the printer?

Thanks for the update from VCF East, Fran! I can't wait to see the cool things at VCF Southwest this year. It might be sacrilege to some, but I've got a TRS-80 Model 4 with an LCD screen replacement that I'll be bringing there.

Wow cool Long ago fun

Thanks for sharing, exciting. Cheers

4096*12 bits to be more clear about memory. The PDP8 is a 12 bit machine.

0:22 sorry, FORTRAN compilier (-IV or-66 ?) worked on this machine in 4K or other machine compiled binary code for it?

Das Blinkenlights!

is there a version of linux that would work on a PDP-8?

Germanium made dendrites. You could run them cool all you like, but a dendrite will kill a Ge semiconductor. Schottky semiconductors have similar knee voltages, but are much faster and don't form dendrites. Knowing this, now I want to build one.

❤️‍🔥

Should have played "Daisy" instead....

HP2100 in the background.

yeah stuff to do after hours... or you know just do it during work hours

Yes, 4K memory. But not 4K bytes....4K 12 bit words.

Can someone close the ross opengear frame door please? Lol

I was born in 1965.

What does the KITT program look like? LOOP1, ISZ DELAY; JMP LOOP1; RAL; SNL; JMP LOOP1; RAR LOOP2, ISZ DELAY; JMP LOOP2; RAR; SNL; JMP LOOP2; RAL; JMP LOOP1 I think might do it (untested). At 1.5µs per core fetch we have 3µs*4096 = 12ms or 144ms per scan, a bit fast. So, maybe: LOOP1, JMS DLY; RAL; SNL; JMP LOOP1; RAR LOOP2, JMS DLY; RAR; SNL; JMP LOOP2; RAL; JMP LOOP1 DLY, 0; DLYLP, ISZ DELAY; ISZ DEL; ISZ DELAY; ISZ DELAY; ISZ DELAY; ISZ DELAY; JMP DLYLP; JMP I DLY So, here it's about 5x slower. ISZ DELAY won't count 5x faster, because 5 and 4096 are co-prime, it'll still do 4096 loops.

Why isn't it in a Climate Controlled box?

But can it run Blender 4.0? How do I install the latest Nvidia GPU-loaded graphics card? Hmm, I suppose it might be a bit underpowered for my needs.