Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!ut-emx!dell!mustang.dell.com!jrh
From: jrh@mustang.dell.com (jrh)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Cache control on 386 PC/AT compatibles
Keywords: Cache
Message-ID: <4102@dell.dell.com>
Date: 7 Nov 89 22:49:37 GMT
References: <1386@mcrware.UUCP>
Sender: news@dell.dell.com
Lines: 12

Most 386 systems that use the Intel 82385 cache controller will allow an 
application to disable the cache.  In general, to avoid caching a memory
space, make sure the highest bit of any address (A31) is high.  This will
help with adapters with memory-mapping, with page swapping or dual-port
memory schemes which may not like the memory space on the I/O channel being
cached.  Because A31 does not go to the I/O channel and other address lines
are the same, the adapter will respond normally.


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James R. Howard
!s: cs.utexas.edu!dell!mustang!jrh