Diff between 11/20 and 11/45? - TUHS

7 Sep 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.

Cheers,
	Warren

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From: Warren Toomey &lt;wkt(a)cs.adfa.edu.au&gt;
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Subject: KE11-A! (was Diff between 11/20 and 11/45?)
To: pups(a)minnie.cs.adfa.edu.au (Unix Heritage Society)
Date: Tue, 7 Sep 1999 11:10:25 +1000 (EST)
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Hi all,
	I've just answered my own question. Reading thru the 11/20
processor handbook, I see the section on the extended arithmetic element,
KE11-A, which is ``an option to perform multiplication, division,
multiple position shifts and normalization significantly faster than
software routines''.

I also see that unit 1 lives at 777300 - 777316, and the date a.out
executable does this:

230:    TRAP 15			time syscall
232:    MOV #177770,@#177314
240:    MOV #47432,@#177300
246:    ADD #5,@#177304
254:    MOV #7,@#177300
262:    MOV @#177302,@#177304
270:    MOV #5,@#177306
276:    ADD #40622,@#177304
304:    MOV @#177304,320
   . . .

So it looks like I need to add KE11-A support to my emulator :-)

Cheers,
	Warren