[conspire] Not Linux-related, but the oldest computer I've debugged.

[Nick Moffitt]

On 06Dec2023 07:36pm (-0600), Don Marti wrote:
> begin Nick Moffitt quotation of Tue, Dec 05, 2023 at 09:18:54PM +0000:
> > I made a video for my friend's channel, covering the story of how we debugged a bit of code on his department's PDP-12 from 1972.
> > 	https://youtu.be/zcP_Dfgvuo8
> 
> That's a really interesting display...does the PDP-8 have a terminal on a serial port too or does everything have to generate characters that way?  

The PDP-8 doesn't have a default scope display (although some "lab-8" machines had a similar but different scope).  Typically everyone interacted with eights over an ASR33 or VT05.

I cover a bit of how this was done from my unfinished exegesis of Flor Anthoni's 1970s PDP-8 Cookbook:

	https://zork.net/pdp8-cookbook/cookbook.html#type

So that was originally a 20mA current-loop setup of some sort, and it grew a UART over the years (even supporting serial disk access on the UMD PDP-12).  But the instructions for using the teletype boiled down to individual machine instructions!

It's kind of a shock compared to the modern day, where a computer really feels more like a network of little microcontrollers all negotiating the loading of firmware and the interchange of buffer data larger than any PDP-8 ever had installed.

Anyway, the scope display came from the LINC, and they got the idea from the TX-2 (and the first LINC was actually an emulator Mary-Ellen Wilkes wrote for the TX-2).  LINC was a fascinating cost-cutting exercise, and the best intro to its history is probably this talk from the 1980s:

	https://yewtu.be/watch?v=l9YBZo30Ses

One interesting footnote: BART ran on PDP-8s until the 2000s, and for a long time the best PAL assembler was one maintained by BART staff:

	https://packages.debian.org/bookworm/palbart