Extremely CISC instructions

Tom Stepleton stepleton at gmail.com
Wed Aug 25 19:44:28 CDT 2021

Thanks for the suggestions, all --- more than I was expecting! I have
plenty of reading waiting for me now, but I hope people won't let that stop
them from sharing other examples.


On Wed, Aug 25, 2021 at 6:08 PM Josh Dersch <derschjo at gmail.com> wrote:

> On Mon, Aug 23, 2021 at 5:38 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. This request is highly
>> underconstrained, so I have to rely on peoples' good taste to determine
>> what counts as "interesting" here.
> I'll submit the Xerox Alto, with its extensions to the base DG Nova
> instruction set.  It included "CONVERT", used to render font glyphs to the
> screen, and of course the legendary "BITBLT" for transferring bitmaps
> across arbitrary bit boundaries.  Both of these were complicated
> operationst, and the latter revolutionized computer graphics...
> See p. 18 and 22 of
> http://bitsavers.org/pdf/xerox/alto/AltoHWRef.part1.pdf.
> (The Three Rivers PERQ included a similar "RASTEROP" instruction in its
> repertoire, which was similar to BITBLT but also allowed for various
> logical operations to be applied to the source and destination.)
> - Josh

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