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Rebuilding the PDP-8 With a Raspberry Pi
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.
...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...)
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.
Lost at C:>. Found at C.
No, antique cars really aren't. If you don't believe me then I challenge you to drive a model-T on an expressway.
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.
My first "personal computer" was a PDP-8i at Georgia Tech in the late 1960's. The ISy school had one in a small room in the basement with an ASR TTY (33 I think). There was another room with at least one more TTY with punch and you would code on that machine and after signing up for time on the PDP-8i you would take your paper tape in and after toggling in the boot sequence and loading the BIN tape then the Assembler you would run your tape to punch out your assembled program to run on the machine. I may be leaving out a number of steps since that was a while back.
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.
The SBC6120 uses a Harris 6120 CPU chip which is a PDP-8/e-like microprocessor. It has a companion FP6120 front panel with switches and lights, which is a scaled down version of an older modle rack mount PDP-8 front panel. You built them from kits, loads of fun for those who like that sort of thing. Mine has a CF card for the hard drives (a whole whopping 2 MB each under OS/8!). You may be able to find an unbuilt kit, as the maker of the kit, Spare TIme Gizmos, will not be making any new ones going forward.
He's snarky, but there's a point when 'additions' start to harm the machine rather than to improve it. Neon tubes with their associated high voltage and extremely high cycling rate draw a lot of power for not real benefit and introduce electromagnetic noise into the computer. Spinners on car wheels mess with the rotational and steering dynamics of the vehicle and remove one cue to other drivers as to what the vehicle is doing as they can no longer look at the wheels to see if the car is starting to pull forward or not.
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.
Do not look into laser with remaining eye.
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... web ring. Those are infinitely cooler I think.
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.
> 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
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.
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.