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Path: utzoo!linus!decvax!mcnc!ecsvax!sfa
From: sfa@ecsvax.UUCP (Sam Averitt)
Newsgroups: net.micro.68k
Subject: Re: VMEbus problems
Message-ID: <1038@ecsvax.UUCP>
Date: Wed, 8-Jan-86 07:43:59 EST
Article-I.D.: ecsvax.1038
Posted: Wed Jan  8 07:43:59 1986
Date-Received: Fri, 10-Jan-86 06:32:14 EST
References: <1201@gitpyr.UUCP>
Organization: North Carolina Educational Computing Service
Lines: 14



This info comes from Howard Crawford at Telex Terminals in Raleigh NC.
They have been having similar problems using the 8530 with a 64180.
The problem apparently is in the interrupt ack versus vector read
timing. The setup time required by the 8530 between int ack and read
must be met. Otherwise the vector may come out meaningless. There must
also be the right setup time between rec clock and chip clock. The
exact values are in the databooks.
It is also interesting to note that Apple says not to access the 8530
in the Mac more often than once every 2.2 usec. (from Inside Macintosh)
so there must be a fair amount of settling inside the chip.
Wayne Sung
N C State University