Questions tagged [pdp-6]

For questions regarding the DEC PDP-6 computer.

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12 votes
2 answers

Was 36-bits needed for LISP?

Came across a curious claim today about the PDP-6: First, 36 bits was the standard for scientific computing. This extended word length also accommodated LISP, a new language developed for work in ...
Maury Markowitz's user avatar
6 votes
3 answers

Why does PDP-6 Fortran need JSA and JRA?

According to, the JSA and JRA instructions were invented for PDP-6 Fortran. It's a strange claim; now I don't know anything about Fortran, but I find it hard to convince myself that ...
Lorraine's user avatar
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8 votes
2 answers

When was DEFUN added to Lisp?

I don't see DEFUN in a ~1966 copy of PDP-6 LISP. I do see it in a 1972 Maclisp. AI memo 116A from 1967 doesn't have DEFUN. (It does have MACRO.)
Lars Brinkhoff's user avatar
13 votes
4 answers

What are the differences between the various 36-bit computers from DEC?

I want to ask about the PDP-6 PDP-10 various implementations KA-10, KI-10, KL-10 DECSYSTEM-20 What are the differences between these? I'm not that interested in architectural differences, cache ...
Lorraine's user avatar
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10 votes
3 answers

Is there a non-paging ITS for the PDP-6 or PDP-10?

In the late 60s, the Incompatible Timesharing System ran on a PDP-6 without any paging hardware (i.e. an MMU in modern terminology). See the Jargon entry for BLT, for example, which states (my ...
Lars Brinkhoff's user avatar
23 votes
5 answers

Where can I find software for the PDP-6?

We are planning to build a reconstruction of the PDP-6. The project is making a lot of progress, but currently we have a critical lack of software. Does anybody know where we can find software to run ...
fuz's user avatar
  • 1,572