🚀 go-pugleaf

In article <25...@boulder.Colorado.EDU> a...@boulder.Colorado.EDU (Alan T. Krantz) writes:
>In article <70...@milton.u.washington.edu> m...@Tomobiki-Cho.CAC.Washington.EDU (Mark Crispin) writes:
>>In article <1990Sep3.0...@cbnewsh.att.com> w...@cbnewsh.att.com (Bill Stewart 201-949-0705 erebus.att.com!wcs) writes:
>>	HRLOI AC,-1(COUNT)	; Halfword Right to Left Immediate, fill Ones
>>	EQVI AC,ADDR		; EQuiValence Immediate
>		 or
>>	MOVN AC,COUNT		; MOVe Negative
>>	HRL AC,AC		; Halfword Right to Left
>>	HRRI AC,ADDR		; Halfword Right to Right Immediate
>Why make things so compilcated. Why not simply
>	MOVE AC,[-COUNT,,ADDR]	; Load ac with ....

How soon we forget!

The MOVE would be fine if COUNT was an immediate value (a compile-time
constant), but in my examples, it's the name of a register.  The whole
point is that if you don't know the szi6xxxx"b3 e of the vector (or the address
of the vector) at compile time, you cannot do a simple move from a
constant.

ADDR could also be a register (or memory location) by changing the
EQVI to EQV or the HRRI to HRR in the above examples.

If you want another shot, here's a "simple" one.  Put a PUSH in
register 0, and start the CPU at 0.  What happens?  No fair trying it
on a real PDP-10.  You can assume the CPU is a bare machine, but this
will work OK under timesharing on Tenex, TOPS-20, or ITS systems.

 _____   | ____ ___|___   /__ Mark ("Gaijin") Crispin  "Gaijin! Gaijin!"
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  /|\    | |/\| _______  /  \ M...@CAC.Washington.EDU    Omae ha gaijin darou"
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