Rebuilding the PDP-8 With a Raspberry Pi 92
braindrainbahrain writes: Hacker Oscarv wanted a PDP-8 mini computer. But buying a real PDP-8 was horribly expensive and out of the question. So Oscarv did the next best thing: he used a Raspberry Pi as the computing engine and interfaced it to a replica PDP-8 front panel, complete with boatloads of fully functional switches and LEDs.
Gotta call out lots of the internals in parallel.. (Score:3)
...so that you can wire up more MSI TTL to add instructions or other features. That's the charm of the old-school PDP-8. (Okay, not the really old-school DTL version, but the version I remember in a friend's dorm room...)
Re:Gotta call out lots of the internals in paralle (Score:0)
How does it boot? I hope it's the real way, with toggle switches (you had to load a program to get it to bootstrap itself). I spent many wasted times booting these things up. Magic incantations and/or curses were optional, but became almost mandatory after a while.
Re: Gotta call out lots of the internals in parall (Score:1)
You toggle in a few instructions to get it to load in your operating system, or compiler, off the high speed paper tape reader. In my case while in college, it was to load the FOCAL time sharing system, so three or four of us could write and run programs at ASR-33 teletype terminals.
Re: Gotta call out lots of the internals in parall (Score:2)
A friend of mine was able to pick up a cheap used PDP-8 in the 1990s with many of the bells and whistles (paper tape reader/writer & teletype, etc), and a full set of software. I remember toggling in the bootstrap loader to start the whole bootstrapping of the operating system. Ah...memories.
Noscript hell, no thanks (Score:0)
Anyone have a link to a less sucky version of the article?
Re:Noscript hell, no thanks (Score:0)
Thank you for that comment.
Hack-a-Day features great content, but they bastardize it with
some of the worst presentation skills on the internet.
If there is a contest for "Worst Presentation" they should win.
People who read HAD don't want "cool" webpages.
They want clear and well organized webpages.
The folks behind HAD have a great product - they just don't know
how to package it. pity.
Re:Noscript hell, no thanks (Score:0)
And that's fucking sad. It's a static fucking web page with some text, some images, and at most an embedded YouTube video. Fuck this Web 2.0 shit, and fuck the web designers who made it a default behavior for blogspot.
Ah, PDP8 (Score:2)
I programmed a PDP8 in Fortran. In the good old days....
Re:Ah, PDP8 (Score:3)
We also had a paper tape based 4K 2Pass Algol compiler that worked, it waited until you reloaded the freshly punched tape of intermediate format to start the next pass and gave you an loadable paper table on the final pass.
Not bad for a machine that had 8 Opcodes.
Re:Ah, PDP8 (Score:3)
Oh, the paper tape... When I was a Comsomol member there were FS-1500 tape readers made in Chechoslovakia. They were really high speed - 1500 bytes per second. The tape just flew through them nonstop. When the first Western readers arrived (made in Poland by US license), they were slow as snails. But the Western tape punchers were really good.
Re:Ah, PDP8 (Score:2)
Interesting; things apparently regressed before they could progress. The first paper tape reader for a computer (Colossus [wikipedia.org]) read at 5000 characters/s in normal operation, and could be cranked up to 9700 char/s (85 km/h), but the tape wasn't strong enough to survive that speed for long.
Of course, the Official Secrets Act made sure the Colossus design wasn't available on the open market.
Cut My COmputing eye teeth on the original (Score:0)
PDP 8/I was the first computer I worked on. Operating system TSS 8.22D, programing language PAL-D (twos complement math) , whopping 16K of memory. We had to use the front panel toggle switches to toggle in a program that when you executed it would read a program stored on paper tape into memory so we could boot off the hard drive. You could use assembler to make the panel lights do funny things to frighten newbs. What a hoot. Hope this person has as much fun as I did.
Re:Cut My COmputing eye teeth on the original (Score:2)
Re:Cut My COmputing eye teeth on the original (Score:3)
When my first PDP-11/70-like arrived I just took a random book from it's dox. After 2 hours of reading I got a terrible headache, threw RSTS away and installed Unix v.6. It was needed to make a binary patch of Fortran-4 compiler to make it understand Russian but we made a really useful system. We had 5 terminals and forgot about the machine time allocation sheets. And students who did the graduation practice printed their graduation works with printers, not with mechanical types. It was a little victory.
The time allocation sheets went back when IBM PC arrived (1988). It was a good eye candy not applicable to anything serious. And only about 1998 IBM PC became powerful enough to replace the PDP-11.
Re:Cut My COmputing eye teeth on the original (Score:2)
Gompers secondary?
Re: Cut My COmputing eye teeth on the original (Score:1)
Re: Cut My COmputing eye teeth on the original (Score:1)
Re:Cut My COmputing eye teeth on the original (Score:1)
Why??? (Score:0)
"Hacker Oscarv wanted a PDP-8 mini computer" the question needs to be asked... why? This is part of humanity I just don't understand. An infinite number of useful potential projects lay before me and the thought of playing around playing with or restoring 'vintage hardware' is just opportunity cost.
Re:Why??? (Score:5, Insightful)
I've long since stopped asking why, and just gotten on with "why not?"
Building a replica of a platform gives you the experience of doing it, the understanding of the process, familiarity with the tools you're using ... and possibly some bragging rights among your fellow nerds.
Why pimp out your CPU case with neon? Why put spinners on your rims? Hell, why have cars anything other than black, which should suffice for anybody? Why play video games? Why watch TV?
None of these accomplishes anything other than filling in time or soothing your own need for something you think is cool.
To you, it's opportunity cost. To someone else, it's "why the hell not?" It's something to do they find amusing.
Compared to half the crap you see on YouTube or anywhere else with humans ... I don't see this as being worse than anything else.
With all the dumb crap humans do every day, there's at least some coolness to this.
And I'm betting you can identify at least 10 things you do every week which you couldn't answer "why" if pressed on the issue.
Re:Why??? (Score:-1)
Why pimp out your CPU case with neon?
Because you are an idiot.
Why put spinners on your rims?
Because you are an idiot.
Re:Why??? (Score:2)
Snark from an anonymous coward is about as useful and purposeful as any of my examples.
Ergo, by your own logic, you are an idiot.
Re:Why??? (Score:4, Insightful)
There are tradeoffs between aesthetics and functionality. Sometimes the majority of the population feels that those aesthetics are worthwhile and sometimes they don't. Personally I want the indicators on my computer to actually convey something, so having a huge light behind a large transparent open panel in the side that's on just because the computer is powered on doesn't help me while individual indicators for fans and disks could. On the other hand, if I spent considerable time and skill dremelling-out a logo through the side panel, then perhaps the powerful light might actually add something to the experience.
If someone wants to reimplement some antiquated hardware for their own kicks that's fine. I've got dumb RS-232 terminals on my desks at both work and home, so I am not immune to this either. I don't expect others to find it cool either though, as there aren't that many people that grew up pre-GUI or in the BBS days in this hobby anymore, so I do it for myself, not for anyone else's approval.
Re:Why??? (Score:1)
Re:Why??? (Score:0)
He isn't wrong.
Re:Why??? (Score:2)
The things you learn re-inventing the wheel can be applied in various parts of your future projects.
It's like asking why solve a math problem? Obviously, to learn how to do math for the chance that you see a problem that you DON'T have an easy answer already available. Hell, that's what an entire engineering degree is. It's not "can you solve problem X" because problem X will almost never occur in real life in an isolated environment. The purpose is "can you solve these kinds of problems." And how do you learn to solve problems? By looking at ones people have already solved.
Re:Why??? (Score:2)
> Hell, why have cars anything other than black, which should suffice for anybody?
You don't live in a hot, sunny place, do you? :-D
Re:Why??? (Score:1)
Hell, why have cars anything other than black, which should suffice for anybody?
Ahem. I drive a stripped-model black Ford Ranger. It's about as equivalent a Ford to the Model T as was made in 2006.
Re:Why??? (Score:1)
Re:Why??? (Score:2)
Re:Why??? (Score:3)
No, antique cars really aren't. If you don't believe me then I challenge you to drive a model-T on an expressway.
Re:Why??? (Score:-1)
You just picked ONE antique car model and pointed out a speed limitation with it. Bravo /sarc, but that's not the point. The right antique cars appreciate in value over time. It's just another asset to add to your portfolio.
Re:Why??? (Score:2)
A Model-T would serve my driving needs 200+ days a year without any significant change to my routines. It could probably serve me another 50-100 days a year if I'm willing to take a little longer to get to places further away than work that I normally take the freeway for.
Re:Why??? (Score:2)
What would it cost to buy?
How much maintenance would it require?
Special fuels? Kind of oil? Required additives?
Suspension and handling? Comfort?
What would potholes do to it?
Now compare all of that to an older but still decent condition used modern car that is way easier to find and obtain.
Now why is the model T still useful?
Note.. I'm not arguing that it might not provide the owner with some form of enjoyment. I like all sorts of things that I do not consider ot be 'useful'.
Re:Why??? (Score:1)
No, antique cars really aren't. If you don't believe me then I challenge you to drive a model-T on an expressway.
At least it's faster than a Tesla.
Re:Why??? (Score:1)
Oh, sorry, I just double-checked, and the Tesla did just win the race :).
Re:Why??? (Score:2)
It is still faster than this Tesla:
http://en.wikipedia.org/wiki/N... [wikipedia.org]
As he doesn't move around too much anymore.
Re:Why??? (Score:2)
Re:Why??? (Score:2)
Re:Why??? (Score:0)
It's the wrong analogy. What this guy has done is the equivalent of putting an antique car KIT on a modern car frame so that it appears to be an antique car.
Re:Why??? (Score:1)
Now go kill your gramps because frankly he's outdated and society's resources could better be spent on someone younger.
Re:Why??? (Score:2)
Re:Why??? (Score:0)
Why did you waste time on Slashdot asking that question when you could have done something useful that had objective return?
No everybody needs to answer to your particular idea of what their time, effort or money should be used for. People are allowed to do things because it makes them happy. They don't need a reason, they only need to enjoy it. Do you partake in any particular form of entertainment? Being entertained is not particularly useful, it just "wastes" time.
Here's some advice: If you don't understand why somebody would want or do something, then maybe it's not for you. It's ok to not understand but don't act like the person who does is a complete idiot for not feeling the same way about it. To most of the rest of the world, being really into computers is a waste of time.
Time you enjoyed wasting isn't wasted.
Re:Why??? (Score:0)
Same reason why some pilots prefer flying Piper Cubs over flying jets.
Or why folks prefer old muscle cars over today's cars.
Or why many photographers prefer film over digital.
I used a PDP-11 and I actually kind of miss it. Booting it up by flipping orange and white switches and hitting "Run" and "Halt" on the front panel ...
Writing a program and just a program and not having to worry about UI, bells (OK We did have bells), eye candy, "user experience", yadda yadda yadda ...
We wrote a program to help solve a problem. We had to actually think about hardware - it wasn't an abstraction like it is today.
Computers weren't a toy or gadget - they were a piece of expensive hardware that you used because you needed it.
And this guy ... jeeze, some of that old shit is on the scrap heap. I don't know why he found it to be expensive.
And ... oooooo Matlock is on!
Re:Why??? (Score:2)
Re:Why??? (Score:2)
Same for me. But you could install a memory rack over the i/o rack in processor box and find a HDD controller instead of removable packet drives. It would give you an usable PDP-11 in a half-height 19-inch rack (Processor/memory, FDD and HDD in it, magtape controller). I fed my PDP-11 from a simple outlet while the electricians invented the special attachment.
Re:Why??? (Score:0)
I just lump these guys in with the Civil War reenactment bunch.
Re:Why??? (Score:0)
“We are on earth to fart around. Don’t let anybody tell you any different.” – Kurt Vonnegut, A Man Without a Country
"If it makes them happy, and it makes me happy, why should anyone care?" – Linus Van Pelt
Re:Why??? (Score:2)
Nostalga. I used to have a beer fridge sitting inside of an old S/370 system cabinet. Sure it took up 20 times the space but it was still cool to look at in the garage.
Re:Why??? (Score:2)
While people might wrap up their reasons in something with more authority or social support behind it, ultimately, most projects we do are 'because it is cool'.
Re:Why??? (Score:0)
Because not everyone is a soulless accountant?
Re:Why??? (Score:0)
> Because not everyone is a soulless accountant?
Ironic because the hippies back in the '60s called people who loved computers "soulless accountants."
Raspberry PI? (Score:2)
I don't know anything about the PDP-8, but isn't using a Raspberry PI completely overkill? Wouldn't a much more basic ATmega328P be enough for the task?
Re:Raspberry PI? (Score:1)
Re:Raspberry PI? (Score:0)
>> I don't know anything about the PDP-8, but isn't using a Raspberry PI completely overkill?
> He should have gone for a PDP-11! As an aside, simh is a really awesome piece of software.
But it's just as hard to find a working PDP-11, and even if simh runs on it, would it be fast enough to emulate a PDP-8? :)
Re:Raspberry PI? (Score:0)
Are you kidding? That machine had as many as 8 instructions! And 12-bit memory. And, uh, that's all I remember.
Re:Raspberry PI? (Score:3)
Ya, it's kind of a non-story really. Ok, he used a replica panel, and you can't just buy those online easily. But a raspberry pi running an emulator is just decidedly not geeky. I can run Unix version 1 and 6 and BSD 2.9 on my Mac and PC, but I don't tell people I rebuilt a PDP-7 or PDP-11 or VAX.
Meanwhile there ARE people out there who have built real computers and CPUs from scratch as a hobby, without any emulators behind the scenes. Check out the http://members.iinet.net.au/~d... [iinet.net.au] web ring. Those are infinitely cooler I think.
Now build me a pocket-sized Cray X-MP (Score:2)
FPGAs (Score:4, Interesting)
We really should be preserving old computers in HDL in a form as loyal as possible to the original. Then we could always reimplement them in FPGA and make "real" hardware cheaply enough until the sun burns out.
It's doable, although these are big efforts.
There is already this Japanese guy who has done it for the SNES [at-ninja.jp].
Re:FPGAs (Score:1)
I was about to post this. In fact, I bet the resulting HDL code for this particular computer can be implemented in a technology that's cheaper than FPGA, like perhaps commercial flash PLD. Also things seem to be moving towards OpenCL which is behavioural and C-like, which may help people who are used to that paradigm, like people who do MCUs including the Raspberry Pi.
Fond Memories (Score:5, Interesting)
in any case that was my first taste of writing any code in a machines assembly language and even then I dreamed of having my very own PDP-8.
This is a cool project and even for an Old Man I can fully relate to why it was done. I think this experience led to a life long career working with computers ranging from Big Iron mainframes to PC's networks and a variety of internal and Internet facing Servers. Yes, even though retired, I have a couple of Arduinos and Raspberry Pi's around to play with! Learning new things has kept me going all these years.
Re:Fond Memories (Score:0)
We had a PDP-8i in my high school in 1977. I think it had 4 or 8K RAM. I remember manually toggling in the bootstrap code on those front panel switches (7737, 3377, etc) before the paper tape would load in the ASR-33 teletype. We had a choice of two languages: Basic or FOCAL. After loading Basic, you had about one or two typed pages of memory left for writing your program, which you could then save on the paper tape.
After basic started up, you could choose not to load the floating point support. That would get you up to about 4 pages worth of code.
By 1978, the school went all high-tech and added an optical paper tape reader.
Yuo fai7 +it.. (Score:-1, Redundant)
SBC6120 is real PDP-8 style hardware (Score:4, Interesting)
Re:SBC6120 is real PDP-8 style hardware (Score:0)
Any website that sports a "Made with Frontpage 2000!" logo gets my money!! Woohoo!!
moron.
Re:SBC6120 is real PDP-8 style hardware (Score:0)
Joke's on you because they sold out years ago.
Double moron.
Re:SBC6120 is real PDP-8 style hardware (Score:0)
I built one of these kits.
It is a great project and it looks great sitting on my book case.
Re:SBC6120 is real PDP-8 style hardware (Score:1)
Why not a PDP 11? (Score:2)
The 8 was a great system but the 11 was far better.
Just checking ebay, this guy selling the 8E is smoking something [ebay.com]. He thinks it's a mainframe.
However this PDP-11 [ebay.com] can be had for a reasonable price.
The point being, you can run emulation software [vandermark.ch] on commodity hardware but I guess as the TFA indicates he wanted the nostalgia look. He could have easily just mounted an LEDs behind the panel with small pattern generator circuit instead of using the Pi.
Re:Why not a PDP 11? (Score:2)
Learned on a PDP-5 (Score:1)
I first learned machine language on a PDP-5, which was similar to the PDP-8, but limited to 4KB of memory. Mostly I just used it to toggle in small programs through the console switches, but I think we got the FOCAL [wikipedia.org] interpreter running on it at one point. Those were the days. To think now there is a generation of programmers who have known nothing but JavaScript.
It reminds me... (Score:0)
Of the old Unix fortune cookie program: One of the fortunes was:
Q: What is the biggest problem implementing a Jerry Ford emulator in 8K memory on a PDP8?
A: Figuring out what to do with the other 4K.
Why would a PDP8 be expensive? (Score:2)
Re:Why would a PDP8 be expensive? (Score:2)
You would think a PDP8 would be worth little more than scrap at this point.
Which is why almost all of them were scrapped years ago. And anyone who is still running something on one really, really, needs spare parts.
Re:Why would a PDP8 be expensive? (Score:1)
Re:Why would a PDP8 be expensive? (Score:0)
It's much larger than your phone and much more expensive to ship somewhere.
Re:Why would a PDP8 be expensive? (Score:2)
Absent interference in the market by governments and/or corporations, price is determined by supply and demand, not capability. I can't think of any rational reason for anybody to interfere with the market for PDP8s, so I'm going to assume it's a free market. Although economic theory with its neat little graphs might give one the impression that it's some kind of science, the actual shape of the supply and demand graphs (and thus the equilibrium price) are determined by emotional "ugly bags of mostly water".
Re:Why would a PDP8 be expensive? (Score:2)
My cellphone has more storage and processing power. You would think a PDP8 would be worth little more than scrap at this point.
You know, at some point things stop being "old toys", "old cars", and "old computers that aren't powerful enough to do anything moden on", and become antique, and collectable.
Re:Why would a PDP8 be expensive? (Score:1)
Dusenbergs are expensive now, too. So are Pierce Arrows.
Even though you can get a used Dodge Neon for a lot less.
He was a little too late (Score:0)
I would have given him a PDP-8 and a couple of 11s (11/24, 11/34) if he'd asked me three or four years ago. Scrapped now!
Re:He was a little too late (Score:1)
Expensive?? (Score:2)
Are old PDP8s really expensive? But I bet no one saved the boxes they came in...
Re:Expensive?? (Score:1)
Re:Expensive?? (Score:2)
I think most 8's came on a pallet, Not a box.
PDP 11 4A (Score:0)
More like PTSD 11 if you dropped that shoe box of punch cards on your way to the computer lab...
(PRO TIP: Clearly number the BACK of your cards so that if they do get mixed up you can sort them without an aneurism!)
173010 !!! (Score:2)
The 6100 Processor- an authentic PDP-8 in hardware (Score:1)
For people who want to build a real hardware silicon PDP-8 computer, there exists an LSI version of it, the Harris/Intersil 6100 processor [wikipedia.org]. It's a standard 40-pin package integrated circuit.
It's a static CMOS processor that can be clocked down to zero hertz if you like (the registers don't need 'refreshing' so it can be clocked as slow as you like) and it's a 12 bit processor and implements the PDP-8 Instruction set.
They haven't been made for years but they exist in NOS (new old stock) quantities and can be purchased at times.
It's certainly more interesting to have a real hardware implementation of a PDP-8 and the 'cheap' way is with a 6100 processor.
Re:The 6100 Processor- an authentic PDP-8 in hardw (Score:0)
You'll have a hard time finding someone to hand-weave the magnetic memory core.
BESM-6... (Score:2)
I'd like to make a BESM-6 emulator with PIC18. But nobody knows it's privileged instructions for now which means that it's impossible to recreate it fully.
PiDP + many real PDPs @ VCF East next month (Score:1)
Re:PiDP + many real PDPs @ VCF East next month (Score:1)
You could always build one from TTL (Score:1)