another RT card in PC question

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2 total messages Started by John F Carr Tue, 29 Dec 1992 22:57

#1215

Author: John F Carr
Date: Tue, 29 Dec 1992 22:57

22 lines
1498 bytes

I'm planning to buy a 486 machine soon, and I'd like to be able to use the
IBM RT apa16 graphics adapter and monitor in it as a second monitor.  The
apa16 card is memory mapped at addresses D80000 to D9FFFF on the ISA bus;
this address range is normally used by RAM.  Is there any way to get this
address range to pass through to the ISA bus instead of referencing system
memory?  What if I put the card on an EISA bus?  I'm guessing it will
respond to any address with the low 24 bits in the range D80000 to D9FFFF.
Is there a way to map some part of memory above 16 MB to pass through onto
the EISA bus?

I haven't said specifically what hardware because I haven't decided yet.  If
this makes a difference (some motherboards can do what I want, some can't)
I'd like to know.

(For PC users wondering how this card worked in the RT: the RT maps the
entire I/O bus into a 16 MB memory segment which does not overlap RAM.  For
DMA, I/O bus addresses get translated to RAM addresses.)


--
    John Carr (jfc@athena.mit.edu)

Re: another RT card in PC question

#1219

Author: Pim Zandbergen
Date: Wed, 30 Dec 1992 17:35

14 lines
1154 bytes

jfc@athena.mit.edu (John F Carr) writes:


>I'm planning to buy a 486 machine soon, and I'd like to be able to use the
>IBM RT apa16 graphics adapter and monitor in it as a second monitor.  The

Almost the same subject; I wonder if it would be possible to put the
IBM RT Megapel adapter in a 486 system (It is supposed to emulate a CGA adapter)
and port the X11R5 AOS server to 386BSD running on this system.
-- 
Pim Zandbergen                      domain : pim@cti-software.nl
CTI Software BV                     uucp   : uunet!mcsun!sun4nl!ctisbv!pim
Laan Copes van Cattenburch 70       phone  : +31 70 3542302
2585 GD The Hague, The Netherlands  fax    : +31 70 3512837

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