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Mark P. markp at valid.UUCP
Tue Jan 20 03:51:27 AEST 1987


> > Then there's the apocryphal story about the PDP-11's sign extend
> > instruction.  The mnemonic op code was, of course, SEX.  That one got
> > changed to SXT before the manuals were printed.
> 
> The Motorola 6809 sign-extend instruction is SEX.
> 
> The PDP-11 may be SEXless, but it does have an SOB (Subtract One and
> Branch).  [Most 11's do.  Old 11's without EIS don't.]
> -- 
>   John Bruner (S-1 Project, Lawrence Livermore National Laboratory)
>   MILNET: jdb at mordor.s1.gov		(415) 422-0758
>   UUCP: ...!ucbvax!decwrl!mordor!jdb 	...!seismo!mordor!jdb

And then there is the RCA COSMAC 1802 SEX instruction, which sets the X
register to a number between 0 and 15 (immediate operand only), which in
turn determines which of the 16 "general-purpose" (all equally worthless :-))
registers can be used in the indirect mode at any given time.

	Mark Papamarcos
	Valid Logic
	hplabs!{ridge,pesnta}!valid!markp



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