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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...)
Anyone have a link to a less sucky version of the article?
I programmed a PDP8 in Fortran. In the good old days....
no, I don't have a sig
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.
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?
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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.
Why would someone want an antique car?
You're looking at it wrong. You are trying to understand it using economics, and of course it wouldn't make sense from that standpoint. He is probably looking at it from an emotional or respect standpoint, or a desire to understand those people that came before him, and that is worth more to him.
Now go kill your gramps because frankly he's outdated and society's resources could better be spent on someone younger.
The car is useful.
I've got some dino DNA to sequence.
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.
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!
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.
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.
Lost at C:>. Found at C.
I just lump these guys in with the Civil War reenactment bunch.
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.
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.
The 8 was a great system but the 11 was far better.
Just checking ebay, this guy selling the 8E is smoking something. He thinks it's a mainframe.
However this PDP-11 can be had for a reasonable price.
The point being, you can run emulation software 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.
Harrison's Postulate - "For every action there is an equal and opposite criticism"
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.
Harrison's Postulate - "For every action there is an equal and opposite criticism"
I could commute with a Model-T. I live ten miles from work and while I usually take the freeway, I could drive on surface-streets the entire way and add no additional distance to the drive and probably only take another ten minutes to make the trip. I wouldn't even be impeding the flow of traffic either.
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.
Do not look into laser with remaining eye.
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.
Yeah, I almost bought a surplus PDP-11 from my college surplus about fifteen years ago. Held off because I'd have had to unplug my stove to power it, and my small apartment was not suited to having a minicomputer in it. It would have cost me less than $100 for two racks worth of equipment.
Do not look into laser with remaining eye.
Oh, sorry, I just double-checked, and the Tesla did just win the race :).
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 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 is still faster than this Tesla:
http://en.wikipedia.org/wiki/N...
As he doesn't move around too much anymore.
APK likes to ask for responses to the same things over and over. Maybe he just likes the responses?
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.
My cellphone has more storage and processing power. You would think a PDP8 would be worth little more than scrap at this point.
Shoes for Industry. Shoes for the Dead.
He isn't wrong.
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!
"Why?" is the goto card for people who don't achieve anything.
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.
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.
'Useful' is subjective, esp living in a society where our basic needs are so easily met (at least for the type of person who is likely posting here).
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'.
If an antique car can be classified as 'useful', then so can an antique computer. It can still do all the things a computing machine can do.
Economics is generally a terrible way to try to understand a motivation since, broken down to its roots, it has no value judgements in it. Every economic model or approach takes an outside value preference as an input.
Are old PDP8s really expensive? But I bet no one saved the boxes they came in...
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!)
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.
> 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
Wait, no, that was the boot loader address for the PDP-11. Never mind.
"Win treats sysadmins better than users. Mac treats users better than sysadmins. Linux treats everyone like sysadmins."
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. 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.
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.
I remember one of my EE classes (microprocessors class? it's been several decades) was basically "how to design and build a PDP-8 using logic gates". One of the more interesting classes I took. Building up the thing from various blocks gave good insight. So, yes, it can be valuable to "resurrect" old hardware.
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.
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.
Oscar is exhibiting his PiDP-8, along with 10 or so other people showing * real * PDP-8s, at next month's Vintage Computer Festival East -- and they'll all be up-and-running, including an original 1965 "Straight-8". Slashdot published a video about the event just a few weeks ago.
I see an antique car being far more useful than an antique computer.
Whilst buying one may be out of the question, it is possible to build a PDP-8 "clone" from raw TTL. I know this was done on at least one college course, and there are books out there to support it...
Because not everyone is a soulless accountant?
“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
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.
CAN-CON 2019 - Ottawa's only book oriented Science Fiction Convention! October 18-20, Sheraton Hotel, Ottawa, Canada h
> Because not everyone is a soulless accountant?
Ironic because the hippies back in the '60s called people who loved computers "soulless accountants."
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'.
You'll have a hard time finding someone to hand-weave the magnetic memory core.