Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!dali.cs.montana.edu!caen!math.lsa.umich.edu!zaphod.mps.ohio-state.edu!menudo.uh.edu!nuchat!xcluud!gtolar From: gtolar@xcluud.sccsi.com (Glynne Tolar) Newsgroups: comp.sys.apple2 Subject: Re: Sharing a SCSI HD Message-ID: Date: 6 May 91 19:55:19 GMT References: <1991May4.064334.3019@nntp-server.caltech.edu> Organization: Greater Montrose UFO Appreciation Society Lines: 40 toddpw@nntp-server.caltech.edu (Todd P. Whitesel) writes: > mattd@Apple.COM (Matt Deatherage) writes: > > No offense, Matt, but I've been wrong on this more often then you :) ... > Here's the Scoop. > > >The SCSI specs say that SCSI implementations may or may not have more than > >one master on the SCSI bus. Apple chooses not to. > > Actually, Apple chose not to do it in the Mac SCSI manager ROMs. It is possib > for Mac SCSI drivers to implement arbitration, although most don't. I had tha > vehemently pointed out to me by someone who writes those drivers. > > The DMA SCSI card ROMs, however, are totally ANSI compliant, including suppor > for full arbitration. This I learned from Matt Gulick himself face-to-face. I'll just let my expirence speak for itself and those who want to can judge if Apple's DMA SCSI card follows ALL the rules. I've connected two DMA SCSI cards to one Seagate ST-296N. One card in a IIgs, the other in a //e. Additionally I tested it with block reads (verify disk) in Copy II Plus. They wasted no time in locking up. When I keep the traffic low on the SCSI bus it works most (but not all) the time. The only thing I could posibly find wrong, besides the DMA SCSI card MAYBE being built wrong, is maybe the Seagate should have not been terminated. By the way the same results occoured with a DMA and a Rev.C SCSI card. I plan to try this again in the future and try a few different things but I better move fast. I'm selling my DMA SCSI because now I have a RamFAST. Note: I know the RamFAST card CAN NOT be used in this enviroment. > Todd Whitesel > toddpw @ tybalt.caltech.edu We don't care, we don't have to. We're Apple computer. ----------------------- OR ----------------------------- Apple II forever. I just love hearing the company LInE. Pick your favorite. gtolar@xcluud.sccsi.com I didn't write the organization or path. I just use it.