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Re: Perplexing GS hardware problem
- Subject: Re: Perplexing GS hardware problem
- From: shack@onyx.southwind.net (Randy Shackelford)
- Date: 1996/12/17
- Newsgroups: comp.sys.apple2
- Organization: SouthWind Internet Access, Inc.
- References: <Pine.SOL.3.91.961205233752.29143A-100000@moose> <32a7c0f4.195148@PersonalNews.Germany.EU.net> <Pine.SOL.3.91.961206193654.17718B-100000@moose> <32a91614.1195387@PersonalNews.Germany.EU.net> <Pine.SOL.3.91.961207165016.26088A-100000@moose> <58jkm7$vm4@seminole.gate.net> <58l4hu$ras@uni.library.ucla.edu> <Pine.SOL.3.91.961212222040.1284C-100000@moose> <Pine.SV4.3.92.961213162230.29400C-100000@bookworm> <5951la$8mk@news.stolaf.edu> <Pine.SV4.3.92.961217074627.2768B-100000@bookworm>
Mark Wade (mwade@suffolk.lib.ny.us) wrote:
: On 17 Dec 1996, Peter F Handel wrote:
: >
: > : DMA has to be disabled on an Apple HS SCSI card if you have more than
: > : 4MB in the memory expansion slot.
: >
: > Are you sure, Mark? I've got an Apple HS SCSI card with a 6MB
: > ram card, and no problems whatsoever.
: I was until you posted that. Are you sure you have DMA enabled?
: Switch 1, the left-most chip, in the "up" position disables DMA,
: in the "down" position DMA is enabled.
: It's always been my understanding that the Apple HS SCSI card can't
: do DMA above 4MBs of expansion memory.
Could be that the system is set up such that the card never tries to transfer
data to the non compatible memory. There could be a RAM disk set up or system
software could be using it. It won't cause a system problem until DMA tries to
happen in the memory above 4 mb.
--
Randy Shackelford
shack@southwind.net