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From: lantz@Apple.COM (Bob Lantz)
Newsgroups: comp.unix.aux
Subject: NuBus Master Cards - recipe for trouble
Message-ID: <47191@apple.Apple.COM>
Date: 7 Dec 90 20:33:06 GMT
References: <1990Nov25.084331.26643@agate.berkeley.edu>   <5005@spdcc.SPDCC.COM> <2158@carroll1.cc.edu> <5151@spdcc.SPDCC.COM> <36544@cup.portal.com>
Organization: Apple Computer Inc., Cupertino, CA
Lines: 22

Fabian@cup.portal.com (Fabian Fabe Ramirez) writes:

>Steve,

>As previously stated, there are NO accelerated video cards whose acceleration
>feature is supported by A/UX.  PLEASE remember that A/UX is a completely
>different OS and thus, the data structures are completely different than the
>Mac OS.

Although A/UX uses the same data structures as MacOS (indeed, we have 32-bit
QuickDraw, etc..) A/UX (and other virtual memory systems for the Mac) pose
some problems for NuBus cards which expect to have direct access to the Mac
address space.  In MacOS your physical addresses and virtual addresses are
generally the same (with some exceptions,)  whereas in A/UX they are not.  

Also, you can imagine problems in allowing one user to control a NuBus card
which has direct access to the physical memory of the system.

>Fabian Ramirez
>SuperMac Technology
>fabian@cup.portal.com
>sun!cup.portal.com!fabian