Extremely CISC instructions

Diane Bruce db at db.net
Tue Aug 24 05:34:25 CDT 2021

On Mon, Aug 23, 2021 at 09:09:55PM -0400, Paul Koning via cctalk wrote:
> > On Aug 23, 2021, at 8:38 PM, Tom Stepleton via cctalk <cctalk at classiccmp.org> wrote:
> > 
> > Hello,
> > 
> > For the sake of illustration to folks who are not necessarily used to
> > thinking about what computers do at the machine code level, I'm interested
> > in collecting examples of single instructions for any CPU architecture that
> > are unusually prolific in one way or another.
> > ...
> > Although I don't know it well, I suspect VAX will place well in one way or
> > another.
> Indeed. Just its addressing modes, with indirection and two separate register indexing operations, are hairy enough.  Then consider the decimal arithmetic instructions that might have up to 6 operands.

And who can ever forget the built in CRC instruction?

Amusingly it was demonstrated that many of the CISC instructions were
faster if one just did them with the 'normal' instruction set.

db at FreeBSD.org db at db.net http://www.db.net/~db

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