Online PDP-8 Home Page, Run a PDP-8 | Hacker News Reader

Online PDP-8 Home Page, Run a PDP-8

pdp8online.com

71 pointsaccrual23 comments

This is the site that convinced me to seek out and buy a PDP-8 of my own back in 2008. Not a PiDP-8, a 1971 PDP-8/e with 12KW of core memory, a TU56 DECtape, a VC8E vector boardset, and a couple teletypes. And then a '73 8/m. And a '75 8/f. And many, many boards and gizmos. And and and. It's been a 6-digit...mistake? Investment? Hobby? Labor of love?

They're not particularly powerful computers, particularly in 2023 - basically a microcontroller in today's terms - but man are they visceral.

SIMH does a good job of letting you run PDP-8 software, but if you want to poke around inside a PDP-8 I really recommend Brian Shelburne's PDP8MAIN simulator (for DOS, but runs perfectly in DOSBox). You can get everything you need here: https://github.com/rrutt/PDP8/tree/master

A PDP-8 programmer's reference from 1969 is available here: http://www.bitsavers.org/pdf/dec/pdp8/handbooks/IntroToProgr...

It's a lovely system. Extremely minimal, but capable and entertaining.

> but man are they visceral.

This is what I find so interesting about these old machines. You can see, feel, and hear them computing in the open. One could easily probe all over and find signals. They soak up power and are beasts of machines, yet they could run modern-ish software if coerced. Fascinating.

> DOSBox

I would highly recommend PCem instead, DOSbox has a bunch of quirks that make non-gaming software fail in unexpected ways. I've been down this unfortunate rabbit hole...

PCem does require a bit more setup than DOSbox, but once you have a system configuration or three in place, it is just lovely to use.

86box is another alternative. Last I checked it was updated more frequently than PCem, but times may have changed.

https://86box.net/

DOSBOX-X it's faster and it uses far less resources than PCEM/86box.

To get an idea just how simple a PDP8 is I built one for Tiny Tapeout a year ago

https://github.com/MoonbaseOtago/tt03-pdp8

It fits (just without the multiply extension) into one cell and looks like:

https://gds-viewer.tinytapeout.com/?model=https%3A%2F%2Fmoon...

That's incredible - did you get the chip back and did it actually work?

Tiny Tapeout's take many months - I expect it before the end of the year

End of the year is pretty soon!! Good luck, and I hope you can post some results once you get the board.

You rock!

The project manager is still alive at 85. Here's his linkedin

https://www.linkedin.com/in/edson-decastro-1240aa12/

He was also featured in Soul of a new machine in his stint founding Data General.

Looks like he's been retired for some time...

Wow.

Hahaha, thanks for the flash back. Waaay back in m1975 when I was a freshman in college studying EE one of the first things they made us do is program a PDP8 manually with the switches and load the bootstrap loader for the paper tape. By then I had already played around with an Altair 8800 in high school running basic and cassette so I thought it was stupid at the time but then later I appreciated what I learned about machine code. Very cool web page. Great memories.

Warm memories. I used a PDP8e at school ~1976-1978. It needed to be bootstrapped manually before running the EDU20 BASIC that let a few of us teletype or paper tape our code into it. We'd compete to see who could input the octal boot sequence the fastest but didn't spend any time thinking about what it was we were doing!

Makes me miss the Living Computer History Museum

The Computer Museum of America in Georgia is amazing! They had all sorts of old computers running and on display, including some Cray supercomputers. Recommend a visit if you're ever in the area.

https://www.computermuseumofamerica.org/

In case you didn't know - the Living Computer Museum was just that, but in Seattle. It was founded by Microsoft co-founder and philanthropist Paul Allen (RIP).

The Wikipedia article has a list of the hardware they had: https://en.m.wikipedia.org/wiki/Living_Computers:_Museum_%2B...

Is it ever going to reopen? I'd like to visit in person someday.

Though it looks like you can log in remotely - and not just to emulators but to real hardware systems as well.

for those that aren't aware: https://obsolescence.wixsite.com/obsolescence/pidp-8

It sold yesterday (for $6K) but there was one for sale on eBay.

Does any service archive eBay listings? I found the listing and it has some nice valuable information and photos attached, it'd be a bummer for it to fall into the ether after the listing exceeds a certain age.

> Almost all the switches feel good and have a good click to them. The rotary knob feels good and has good click. The only switch that's questionable is the EXTD ADDR LOAD switch is loose and has a weird tilt to it.

> The cards are: Main full length board (no numbers): Remex, M8330, M832, M8320, M837, M8310, G111, M849, M8300

> Last board doesn't have numbers up top, it says H212on a sticker on the board.

> The boards look to be in good shape. The only questionable one is M832. It looks clean but has a twist to the board. It fits fine in the slots but from about looks crooked.

on ebay as part of the search pane running down the left hand side, there's an "already sold" radio button, will show you stuff already gone by, not sure how far back it goes

Interesting idea. There is a project: bitsavers[1] dedicated to preserving such information. I did look up the board set for the different revisions of the 8/M and compare vs the photos. It looked like the machine had been upgraded from core to semiconductor memory, but the core driver boards left in place.

I'm more interested in pdp-11. I have several hundred sheets of microfiche of docs and source listings, but so far no good way to scan them. Bitsavers already has quite a bit of that material though.

[1] http://www.bitsavers.org/

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