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From: neil@cpd.com (Neil Gorsuch)
Newsgroups: comp.sys.mac.hardware
Subject: Re: Sharing the SCSI bus?
Message-ID: <1989Dec8.232535.14072@cpd.com>
Date: 8 Dec 89 23:25:35 GMT
References: <1989Nov29.030959.27969@Neon.Stanford.EDU> <8252@pogo.WV.TEK.COM> <1989Dec5.165138.5192@Neon.Stanford.EDU>
Sender: neil@cpd.com
Reply-To: neil@cpd.com (Neil Gorsuch)
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Organization: Custom Product Design, Inc., Santa Ana, CA, USA
Lines: 18

I haven't followed this discussion, but here is some information about
the MAC SCSI performance which defines some of it's implementation:

1. We only see 250 Kbytes per second data transfer rates, as opposed
to 2.5 Mbytes per second on other machines, using our new scsi box.
The MAC obviously uses the CPU in a tight loop, instead of using DMA
like most workstations do.

2. The MAC doesn't use a SCSI interface chip, since it doesn't
tolerate fast multiple transitions between SCSI states, like most
workstations do.  You have to allow time for the MAC processor ro
notice every state change.

--
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