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Date:      Sun, 3 Mar 1996 19:14:04 +1030 (CST)
From:      Michael Smith <msmith@atrad.adelaide.edu.au>
To:        tomppa@fidata.fi
Cc:        amurai@spec.co.jp, nate@sri.MT.net, questions@freebsd.org
Subject:   Re: Backup problem
Message-ID:  <199603030844.TAA06667@genesis.atrad.adelaide.edu.au>
In-Reply-To: <199603021758.TAA05633@zeta.fidata.fi> from "Tomi Vainio" at Mar 2, 96 07:58:57 pm

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Tomi Vainio stands accused of saying:
> 
> Atsushi Murai writes:
>  > > AMI SCSI adapter is EISA bus master and it also can do DMA over 16MB
>  > > memory in Adaptec 1542 compability mode  but FreeBSD driver doesn't
>  > > support it.
>  > 
>  > Sounds like you are confusing.. 
>  > 
>  > 	1. Adpatec 1542 compatible mode is impossible to handling
>  >            above 16MB due to 24bit pointer architecutre of firmware.
>  >            So even hardware has 32bit addressing like EISA, driver
>  >            can tell to firmware as 32bit address.
>  >         2. Some old EISA mother board has a limitation to over 24 bit 
>  >            addressing phygically.
>  >
> I have used this card in 1542 mode with 32MB RAM before there was
> operating systems which can handle bounce buffers (year was 1991 or 1992).

This is impossible.  The 1542 programming model only has a 24-bit DMA target
address register.  The driver may have performed the bouncing internally,
but it must have done it.

>   Tomppa

-- 
]] Mike Smith, Software Engineer        msmith@atrad.adelaide.edu.au    [[
]] Genesis Software                     genesis@atrad.adelaide.edu.au   [[
]] High-speed data acquisition and      (GSM mobile) 0411-222-496       [[
]] realtime instrument control          (ph/fax)  +61-8-267-3039        [[
]] Collector of old Unix hardware.      "Where are your PEZ?" The Tick  [[



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