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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