Diff between 11/20 and 11/45?
Dave Horsfall
dave at fgh.geac.com.au
Wed Sep 8 16:29:16 AEST 1999
On Tue, 7 Sep 1999, Steven M. Schultz wrote:
> > MOV SP, -(SP) MOV SP, R0
> > MOV (SP), R0 MOV R0, -(SP)
>
> Ah, thank you for bringing that memory back to the front of the brain!
> If R0 is available for that then yes indeed that'll do the trick very
> nicely.
Yep, I remember that now! Often thought it was odd, but it worked
on all platforms.
The convention was that R0/1 were scratch (used to return results)
and R2/3/4 had to be saved (they were the caller's first three register
variables). R5 was used as a frame pointer (?) and R6/7 you know
better as SP/PC.
> The 11/45 (and 70) behave as "expected" as do the KDJ-11 systems
> (11/73, etc) so unless a person had an 11/40 (or a /20) around it
> would be fairly easy to get bit by the "feature".
We had 40s, and used to dream of owning a 70... I learned a lot about
porting Edition 6 to the /23, /60, etc.
> When it comes time for MMU "features" I know of one difference between
> the KDJ-11 and the other members that had an MMU (11/44, /70, etc). Was
> fun tracking it down but not something I'd want to do again ;)
Do you recall the PC-board hack on the sep-ID machines that changed
the MFPI instruction to do something that was expressly prohibited?
Something about allowing a user program to access something else, for
some obscure hack or other...
--
Dave Horsfall VK2KFU dave at geac.com.au Ph: +61 2 9978-7493 Fx: +61 2 9978-7422
Geac Computers P/L (FGH Division) 2/57 Christie St, St Leonards 2065, Australia
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