TI99: WP and PC

From: Hans B Pufal <hansp_at_digiweb.com>
Date: Fri Jan 29 23:27:59 1999

Jay West wrote:

> >> WP... workspace pointer. back when the 9900 was new registers (memory)
> >> really ate up chip space and TI had an archetecture in the 990
> minicomputer
> >> where register were in memory instead of in the CPU. So the WP is a
> pointer
> >> that points to a block of 16 locations in ram that are addressed in
> >> instructions as R0 through R15.
> >
> >Wow! What a cool architecture! That would be a very handy feature to
> >have in any processor.
>
> Wouldn't that be an awfully handy feature for doing a context switch? It
> would seem simply adjusting WP would perform the appropriate "change of
> personality" to select the next user/process...

Exactly, but the down side was the access time to the registers, they
were all memory accesses and no cache in those days.


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Hans B Pufal Comprehensive Computer Catalogue
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Received on Fri Jan 29 1999 - 23:27:59 GMT

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