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From: terry@cs.weber.edu (A Wizard of Earth C)
Subject: Re: The ultimate 386BSD machine? (FAQ fodder)
Message-ID: <1992Oct9.002810.8664@fcom.cc.utah.edu>
Keywords: 386BSD
Sender: news@fcom.cc.utah.edu
Organization: Weber State University (Ogden, UT)
References: <1992Oct8.072512.8700@elroy.jpl.nasa.gov> <Bvsss4.9nz@ibmpcug.co.uk> <1992Oct8.164919.14096@eab.retix.com>
Date: Fri, 9 Oct 92 00:28:10 GMT
Lines: 45
In article <1992Oct8.164919.14096@eab.retix.com> erik@eab.retix.com (Erik Forsberg) writes:
>In article <Bvsss4.9nz@ibmpcug.co.uk> adrian@ibmpcug.co.uk (Superuser) writes:
>>Julians SCSI system works by setting th 1742B into 1542 mode, and then
>>when the probe works out its a 1742, it shoves the card into enhanced
>>mode itself.
>>
>
>This seems to be a BAD approach. It would EXCLUDE all existing 1740 cards
>from functioning. ONLY the newer 1740A (and obviously 1742A) allows switching
>between standard and enhanced mode at runtime. The older 1740 (which probably
>still is the most common Adaptec EISA card out there) requires you to
>download firmware that is specific to the operating mode.
>
>So, useful support for Adaptec 1740 cards, requires support for enhanced
>mode in everything (boot blocks, standalone boots and kernels).
This is, of course, an alternative. To do so would require reqriting
nearly everything in an "isa" directory in the /usr/src/sys.386bsd
heirarchy. In addition, this would be nearly twice the job of the ISA
code currently in use, because there's no telling if someone will plug
an ISA card into an EISA slot. This means the code must support both
types of cards -- so be prepared to rewrite all the ISA code to fit into
the framework you establish with your EISA bus drivers.
Julian has chosen an alternative that allows you to use 32 bit EISA
transfers with [apparently] ISA cards.
Also, the older (non-A, non-B) versions of the controllers would require
new drivers anyway -- they aren't as "smart" as the newer models, and
the current drivers expect a certain level of intelligence from a card.
So the 1740 has two strikes against it -- three if you don't get a 1742
but want to use a boot disk.
Terry Lambert
terry@icarus.weber.edu
terry_lambert@novell.com
---
Any opinions in this posting are my own and not those of my present
or previous employers.
--
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