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From: michaelv@iastate.edu (Michael L. VanLoon)
Newsgroups: comp.os.386bsd.questions
Subject: Re: Buslogic 742A & >16M RAM
Date: 4 Apr 94 16:16:48 GMT
Organization: Iowa State University, Ames, Iowa
Lines: 23
Message-ID: <michaelv.765476208@ponderous.cc.iastate.edu>
References: <QhbWmK600iM8Q0YJoE@andrew.cmu.edu>
NNTP-Posting-Host: ponderous.cc.iastate.edu
In <QhbWmK600iM8Q0YJoE@andrew.cmu.edu> Timothy J Kniveton <tim+@CMU.EDU> writes:
>it seems that the buslogic emulates isa operation, which would mean
>that it uses DMA address space of only 24 bits, right? which would
>mean that it can only deal w/ 16M. is it true that buslogic 742A can
>only deal with 16M memory?
With any of the current SCSI code the bt742a only grabs the ISA dma to
make brain-damaged DOS software happy -- it doesn't actually use the
ISA dma chip, but just holds it while using its own dma circuitry. In
fact, you can disable the ISA dma grabbing altogether if you use *BSD
with no problems on my bt747s (should be able to on your 742a too;
just tell your card to use no dma in the EISA setup).
The bt742a is fully capable of dealing with 32-bit addressing, and all
current SCSI code uses it in this mode.
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Michael L. VanLoon Iowa State University Computation Center
michaelv@iastate.edu Project Vincent Systems Staff
Free your mind and your machine -- NetBSD free Un*x for PC/Mac/Amiga/etc.
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