Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!wuarchive!texbell!texsun!newstop!sun!imagen!atari!portal!portal!cup.portal.com!phorgan
From: phorgan@cup.portal.com (Patrick John Horgan)
Newsgroups: comp.sys.amiga.tech
Subject: SCSI direct
Message-ID: <27712@cup.portal.com>
Date: 9 Mar 90 05:09:05 GMT
References: <DEVEN.90Mar6142851@netserv2.rpi.edu> <9310007@hpfcso.HP.COM>
Organization: The Portal System (TM)
Lines: 15

I posted a few days ago to note that a friend had found a way to do
SCSI direct on a 2090a.  It seems that a bit that tells the dma
chip whether it should read or write is never getting set, so the
dern thing always thinks it's supposed to read.  The work-around is
to pull up bit 24 of the data buffer address (addr |= 0x1000000) in
your SCSI direct packet when you write.
	Fortuitously, since the 2090a driver isn't setting this when
it's supposed to it also leaves it alone:)  The same code will work
successfully with the 2091.  The driver will overwrite the bit with
it's own.
	The news I got today is that although the 2090 driver doesn't
support SCSI direct, the 2090a driver, (when used with this method),
works just fine with the 2090:)

Patrick Horgan                         phorgan@cup.portal.com