PDP-1D

[PashPaw]

Looking over the source code, it does appear to run on the PDP-1D. Page 38 has a syllable that uses the LAI instruction:

COLON IF  JSP  GNS           /"TRUE" OR "FALSE"
...
                      LAI
...

LAI only appears on the PDP-1D. It is not a part of the "standard" PDP-1 (read: A-C) instruction set. All surviving documentation mentions that it ran on a system that supported remote terminals. Report 1889, from 1969, also mentions the use of the Teletype extensively and that Logo: A Final History confirms that these experiments were on a PDP-1.

[larsbrinkhoff]

Does it look like it's running under timesharing? I'm thinking that in the late 1960s, the BBN PDP-1D would have been running the timesharing system. But maybe they allowed periods of out of timesharing operation as well.

[larsbrinkhoff]

Are we typing this? Or what's the priority with regards to transcription?

[PashPaw]

If you want, you can. I am not prioritizing this over Exec-III for reasons.

As for its dependence or independence of Exec-III:

• The listings mention a symbol, TTNO, for the Type 630 scanner that doesn't appear anywhere else but Exec-III.
• There are no direct instructions for the scanner.
• There are PDP-1D instructions like LAI.

There is another issue looming with both of these, and that's the state of the macro1 cross-assembler. I got some of it working but I need to learn C a little better before finishing that.

[PashPaw]

An addendum: the standard macro1 cross-assembler is missing almost all of the 1D instructions. The ones that were used for Spacewar are in it but it will need to be updated to support the changes to the instruction set. I've added a lot of them already but there are macros that I don't know how to implement.

[larsbrinkhoff]

Ok, gotcha.

What are the hairiest macros you can find? I wouldn't want to a full implementation PDP-10 MIDAS-style macros because that would be a huge job. If the macros in Exec III and LOGO are not too bad, I could make a stab at adding that to marco1.

[PashPaw]

Ok, gotcha.

What are the hairiest macros you can find? I wouldn't want to a full implementation PDP-10 MIDAS-style macros because that would be a huge job. If the macros in Exec III and LOGO are not too bad, I could make a stab at adding that to marco1.

Thanks. I haven't encountered any yet. They all appear to be real instructions at this point. I guess it serves as a warning, however.