Running A PDP-8 From 1965

[@markshaum8364]

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.

[@reasonablebeing5392]

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.

[@James_Knott]

I have a core plane from a Collins 8500. It's also 4K and there were 32 of them stacked together in a memory module, for 4K words or 16K bytes. The computer held 4 modules for 64KB total.

[@timradde4328]

Core memory. I had an 8e with 32k core back in 2000-2010. Sold it to a friend when I moved across the country. I could actually play Adventure on it as that required the full 32 to play it. I have a video of me playing it somewhere. I also had an 8i in my living room with 4 full racks. Wish I still had that now. But it was way too big to move so that got sold too.

[@TokenRing1024]

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.

[@jczeigler]

I was a csc major at ncsu. Worked on the pdp-11 running unix version 6. We found that pdp-8! And I think my friend Mike got it to run a blinkenlights program…

[@TokenRing1024]

@@jczeigler Wow. I have often wondered what happened to it. No one really seemed interested in it when I left although there was a new professor who was interested in computers.

[@daffyduk77]

"personal" as in only needing a forklift truck, not a crane 🙂

[@timradde4328]

@@daffyduk77 Most computers back then took up entire rooms. So this was considered "small". And reasonably priced. The community college where I grew up had an 8i (next in line after this one). It ran TSS/8 so all the high schools in the area had a TTY and a dial up phone to call into it. I was hooked the first time they let us use it. I have always preferred the "blinken lights" computers of those days.

[@jdedourek]

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.

[@basinstreetdesign5206]

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.

[@timradde4328]

I got my first try at a pdp-8i at our local community college. All the local high schools had a TTY and a dial in phone to connect to it as it ran TSS/8. I was hooked. Went into computer science and was a programmer for over 40 years. Those were the days. Ah, paper tape. Used it alot and had all kinds of programs. Biggest was a special version of focal. I think it was titled Focarl. But I think it was supposed to be FocalR. It came on several paper tapes. Took forever to read it in.

[@bobhart677]

My high school had a pdp 8. In 1975. I learned how to program in basic, we stored our programs on paper tapes.

[@timradde4328]

Many smaller colleges had them I think. Our local community college did. It had an 8i running TSS/8 so all the local high schools and junior high schools could connect to it via a TTY and modem phone.

[@LunaticEdit]

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

[@trainliker100]

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).

[@DavidCohen-p9m]

I chose the Intersil 6100 chip because of the low power CMOS to design a portable, rechargeable battery powered, thermometer for Comark Electronics. For battery life it was the only choice at the time. We had an ASIC, then called a 'Custom Chip', manufactured by GEC Semiconductors of Wembley in the UK (a Marconi Group Company) to do all the LCD driving and counting. I even designed my own development/simulator box to store & run the program. To get the precision we had to do triple byte arithmetic and my coding engineer used clever looping subroutines to cut down the memory requirements. Fond memories!

[@trainliker100]

@@DavidCohen-p9m For our applications that were math intensive, we used a floating point package (forget whose) that was simply linked in with our assembly code. You must have done your project almost just as the 6100 came out (introduced Q2 1974) if that's all there was because the 1801 came out in early 1975 and the 1802 shortly after. If you are interested in microprocessor architectures, check out the 1802. It has 16 16 bit registers you can use for all sorts of things. And any can be the program counter and any the stack pointer. Or you can have multiple PC's and SP's. This allows a very fast way to get to a subroutine, but they can't be nested. Also, it has no call or return instruction for conventional subroutines. You have to write a couple of the shortcut scheme subroutines to emulate full call and return instructions if you want nested routines. It is an odd duck, but for some things you can write very compact code.

[@robainscough]

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

[@markurban4766]

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

[@gregebert5544]

I had a chance to play around with a PDP-8 about 40 years ago; I cant recall if it was an 8E, 8M, or 8I. It was a single box with a front panel, but not nearly as featured as the one in the video. It also had 2 DecTape drives, which were nice for running apps like Fortran 2 and BASIC. By salvaging another system, we maxxed this system out to 12K. It was frustrating to use it because the DecTape would frequently hit an error, and the machine halted, requiring a reboot. There was a diode-based ROM board that had enough programming so the system could boot from the DecTape. It's amazing how few instructions this diode board had; could not have had more than 15-20.

[@YAVcc]

Nice! I had a PDP-8L, but it was destroyed in a flood years ago. I'm jealous you have one :)

[@trainliker100]

There might be some museum or the like that could use it. You might consider checking that out and making a donation. There are a LOT of museums for everything. I had an AFCO-64 Executive tape recorder (pretty rare mid-century business-oriented tape recorder with all accessories new in the box) and donated it to the "Museum of Magnetic Sound Recording" (yes, there is such a thing) and they were delighted to get it.

[@skippytheaustralian9438]

I have a TI57 & a HP48 (inop), I' afraid they are too small to be vintage. Seems to me, that a PDP11 ist more vintage than this PDP8.

[@timradde4328]

I had several but sold all in 2010 as I was moving and they were too big to move and too costly too. I wish I had kept the 8e.

[@scottthomas3792]

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

[@Madness832]

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.

[@ghrey8282]

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

[@mrspock2al]

PDP-8 literally changed my life. In college during early 1970s, got my first introduction to programming on a PDP. Learned assembler and an interpreter language called Focal. I was hooked. So what does a math major do for a career - become a computer programmer / systems analyst.

[@timradde4328]

You sound like me. The pdp-8 also changed my life. I was thinking of being a doctor. But our junior high school had a computer class (who knew what a computer was back then. I did not). It was just a TTY with a dial up phone and acoustic coupler to the local community college that had a pdp-8i running TSS/8. 16 users could be supported. I was hooked after my first try at using it. I too learned assembler from the guy that ran the video dept. Got the book from DEC and went from there. I actually owned a pdp-8 for many years and 2 8i's for those same years. Basic and Focal were fun too. Yep, I became a programmer for Sperry Univac and later Lockheed Martin. Now retired and playing with Oscar's pidp-8, pidp-11, and now the pidp-10. All based on Raspberry pi with scaled down switches and lights of the 8i, 11/70, and KA-10 (pdp-10). Nice to meet you here.

[@daffyduk77]

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

[@mikebarushok5361]

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.

[@OldBaloo33]

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

[@АндрейМилованов-у9у]

PDP-11clone

[@darylmorning]

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

[@T3hBeowulf]

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.

[@timradde4328]

Excellent video. I had several pdp-8s between 2000 and 2010. But had to sell all of them as I was moving across the country. So this is a nice way to reminisce.

[@lmantuano6986]

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

[@garyplewa9277]

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.

[@FranLab]

I know they'd want to talk with you. Please reach out to them!

[@jackierabbit450]

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...

[@josephgaviota]

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.

[@sammisworkshops3762]

very cool Fran!

[@KeritechElectronics]

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

[@xjet]

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" 😀

[@johnnystall9683]

Thank you, thank you, this is so fun

[@skippytheaustralian9438]

Me too. Mach weiter so, Dear Fran!

[@James_Knott]

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.

[@gwesco]

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.

[@BlankBrain]

We had a PDP-8 in high school in the early '70s. We had to enter loader manually too. Inputting the loader and loading the Basic interpreter from paper tape took over a half hour. Many times, a program would hang the computer and force a reboot.

[@marc6340]

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!

[@fepatton]

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!

[@andrewallen9993]

Sounds like the ICL 1900 series mainframes.

[@BlankBrain]

I used a CDC 3300 in college. It was the most impressive and beautiful computer I ever saw.

[@kevincozens6837]

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.

[@fik_of_borg]

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

[@richardnaber4182]

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

[@thenoblerot]

Loving this footage from VCF - thanks Fran! ❤

[@BlankBrain]

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.

[@James_Knott]

Ummm... That 4K RAM would have been core. Until solid state memory came along, a few years later, core memory was used in all computers.

[@stevejohnson1685]

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!

[@DrunkenUFOPilot]

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.

[@James_Knott]

Those early systems would also have a head per track disk and a program would bring in parts of the code from it as needed. Data would also be stored on that disk. While head per track disks had fairly limited capacity, they were fast as there was no head movement and latency was dependent on the rotation of the disk under the heads. The sectors would also be interleaved, to maximize the transfer rate.

[@josephgaviota]

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.

[@hotpeppersrcool]

I remember the 11/34 from HS and college. In 1980 orn81 we were already using terminals and running BASIC (happy 60th BD to BASIC - this month, in fact. In college we just used it as a batch loader to send off FORTRAN programs to an IBM 370 to be compiled.

[@josephgaviota]

@@hotpeppersrcool Happy Birthday to BASIC. Excellent point.

[@error.418]

Just casually playing the mother of all demos in the background

[@jackcampbell2479]

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

[@barkeaterden]

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

[@anotherdave5107]

How is it everyone seems to have a PDP in their storeroom/garage or barn!?! I've been opening mine for about 70 years daily and have yet to magically find one.

[@zaxchannel2834]

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

[@skippytheaustralian9438]

Very modern minicomputer, no tubes.

[@davidkaplan2745]

Das Blinkenlights!

[@zodak9999b]

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.

[@rickharold7884]

Wow cool Long ago fun

[@mgraemem]

I had access to the computer lab at my high school back in the day. Someone had an Imsai 8080 programmed to play music via rf noise as this demo was set up for. Yes, computers were more fun back in the day. Now, they're just a commodity product, often an annoying one.

[@АндрейМилованов-у9у]

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

[@octothorpe12]

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

[@nerdyorganist]

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 KZbin videos. Did they have a whole system or just the printer?

[@douglascrawford2563]

We have 2 terminals, a CPU, hawk drive, and printer. It was from Pottstown PA. Dave Lovett did a day long restoration demonstration on Sunday where he tore down cleaned it and did enough restoration work to get both the fix drive and the removable drive spun up.

[@nerdyorganist]

@@douglascrawford2563 that’s great! That had to be the most stable computer system I ever used in my life, we never turned it off, basically 24/7 operation for 20+ years. Well our first system did need some regular maintenance with the hawk drive but we upgraded to the series 12 I believe it was called and that was the one that never needed anything

[@wolfganglohrie6820]

Thanks for sharing, exciting. Cheers

[@kensmith5694]

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

[@davidewing6650]

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

[@dougingraham5807]

No. The max standard config for a PDP-8 is 32k (48k bytes if you do some packing). There was a version of the PDP-8/a which supported 128k (192k bytes packed). It is possible that an early version of UNIX could fit in such a machine but nobody ever did that and linux is far too memory hungry to fit.

[@andrewallen9993]

HP2100 in the background.

[@chaosopher23]

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.

[@IAmPaigeAT]

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

[@framegrace1]

Should have played "Daisy" instead....

[@trainliker100]

I'm not sure everyone will "get" that. It's a bit oblique. And they would have to have play it slower and slower.

[@skippytheaustralian9438]

No, "Daisy" will automaticly wil be performed on shutdowm (Z23s will Play "Hänschen Klein")

[@skippytheaustralian9438]

​@@trainliker100I got it. HAL 9000-computers (1997) are multilingual.

[@framegrace1]

Is not oblique at all. The reason HAL plays Daisy is because A.C.Clarke listen it being played on the first computer that performed this AM radio trick.

[@trainliker100]

@@framegrace1 "Oblique" in this context is in the sense that some readers may not understand it.

[@TheOriginalSnial]

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.

[@filepz629]

❤️‍🔥

[@cuttinchops]

Can someone close the ross opengear frame door please? Lol

[@jdedourek]

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

[@belstar1128]

so 6k ?

[@skippytheaustralian9438]

46.875kiByte

[@iroulis]

Why isn't it in a Climate Controlled box?

[@DrunkenUFOPilot]

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.