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Re: New Vax - future directions :-)
On 2021-07-07 18:42, Anders Magnusson wrote:
Den 2021-07-07 kl. 17:22, skrev Hans Rosenfeld:
No split I/D space, no FP, any kind of trap exits out to VAX mode,
that depends how the memory management of the PDP-11 works will have
issues... Even some instructions you might play with are missing (but I
don't think most people would miss them, especially not since we
split I/D space anyway).
Very few 2.11BSD programs would work in this environment... The most
limitation is the lack of split I/D space.
So I guess we have another few feature requests, then... :)
Maybe add I/D segment registers for PDP-11 compatibility mode?
"Segments"? It's a straight forward page table. The only "odd" thing is
that the page don't have to actually map the whole part of it. But you
have a direct mapping from a specific virtual address to a specific
page. It can't move around, no matter how much you play with the MMU.
If we go for something with 8k pages in the future XVAX it might fit
quite nicely :-)
Yes. Since the PDP-11 pages are 8K it would fit pretty nice. However,
the fact that the PDP-11 page don't have to fill the whole 8K can maybe
throw some wrenches in somewhere.
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt%softjar.se@localhost || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
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