Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!uunet!husc6!bbn!uwmcsd1!ig!jade!ucbvax!hplabs!decwrl!labrea!Shasta!kaufman
From: kaufman@Shasta.STANFORD.EDU (Marc Kaufman)
Newsgroups: comp.sys.mac
Subject: Re: L5380 SCSI chip?
Message-ID: <2314@Shasta.STANFORD.EDU>
Date: Tue, 8-Dec-87 12:01:04 EST
Article-I.D.: Shasta.2314
Posted: Tue Dec  8 12:01:04 1987
Date-Received: Sun, 13-Dec-87 15:05:52 EST
References: <8712072213.AA00774@distance.ads.arpa>
Reply-To: kaufman@Shasta.stanford.edu (Marc Kaufman)
Organization: Stanford University
Lines: 22

In article <8712072213.AA00774@distance.ads.arpa> carl@DISTANCE (Carl Tollander) writes:
-In the November Byte, page 14, there is an article "Controller Chips
-Add More Zip to SCSI".  Mentioned is the Logic Devices L5380 SCSI controller
-chip, which is reputed to double the data transfer rate of the SCSI
-interface.  The article says that the chip is designed to be a direct
-substitution for the NCR 5380, which is used in the Mac.

-After wading through the article, I infer that what we have here is
-actually a chip set, with one used in the hard drive and one used in
-the Mac itself, and that no other modifications are necessary other 
-than to replace the chips.

....
-Has anyone tried this?  I'm not sure that it would be worth it if the
-drive could not take advantage of the extra interface speed.

The 5380 is a very low level implementation of SCSI, and every bus state
transition requires an explicit write to the chip, unless you are using
DMA.  As the Apple does not use DMA for SCSI transfers, I cannot imagine
that there will be any improvement in transfer rate if you change chips.

Marc Kaufman (kaufman@Shasta.stanford.edu)