geof@imagen.UUCP (Geoffrey Cooper) (01/03/88)
I have a very large application that currently runs on 68000 class
machines. I'd like to port it to the PC/AT. I know that it would be
easier to port it to the '386 machines instead, but I want the AT. I
would estimate the program at 1 MB program, 2 MB data. Overlays are
not acceptable because of the nature of the program.
I'd like to use protected mode. In protected mode the virtual address
space is linear; you can treat it as a 24-bit linear address space if
you fill the segment descriptors contiguously. I think that I can get
a compiler that will do 32-bit pointer arithmetic.
My '286 manual indicates that when you load a segment descriptor on
the '286, you get a restartable fault if the segment isn't there.
Since the fault is restartable, I believe that I can pretend that I
have a 24+ bit linear, paged address space, with the page size being
64KB. Q1: is there anything I've missed?
Q2: Has anyone out there done something like this? I'd like to buy a
package that does as much of the bookkeeping of what I've described for
me. I'll pay for it, and I'd pay someone who knows how to create it for
me if there isn't a product out there. Has anyone heard of such a
thing?
(Things I already know: AI architects doesn't do paging and won't sell
sources. Xenix and Microport unices don't page on the '286 (not that
UNIX was what I was looking for))
Please reply directly to me, I don't normally have time to read this
entire list.
- Geof Cooper
IMAGEN
imagen!geof@decwrl.dec.com
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