Diff between 11/20 and 11/45?

Warren Toomey wkt at cs.adfa.edu.au
Tue Sep 7 09:56:09 AEST 1999

Hi all,
	Dennis Ritchie has unearthed some really old Unix a.out
executables from around 1st Edition - 2nd Edition period: see
Distributions/research/1973_stuff in the PUPS Archive.

[ Actually, I suspect his dates are a year off: they should be 1972 ]

I've printed off the 1st Ed manuals from Dennis' web page, and I'm
attempting to get my a.out emulator, Apout, to run these old binaries.

I've got a few working. cat works. ls and date run, but sort of give
strange outputs.

These executables were written for a PDP-11/20. Are there any significant
USER-MODE differences between the 11/20 and later PDP-11 models? I'm
thinking missing instructions, different addressing mode behaviour etc.

There is no source code with these binaries, so I can't use that to help
debug the emulator. I do have the following processor handbooks:

	PDP-11 /20 /15 /R20		1972
	PDP-11 /45			1973
	PDP-11 /04 /34 /45 /55 /60	1978-79

I just thought I'd ask for pointers here before I hit them for details.


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