12.012 What are correct HS SCSI settings, etc. for a Bernoulli drive? My system is as follows:
Description
This article is from the Apple II Csa2 FAQ, by Jeff Hurlburt with numerous contributions by others.
12.012 What are correct HS SCSI settings, etc. for a Bernoulli drive? My system is as follows:
ROM 1 Apple //gs
4mb AE RAM card
8mhz ZIP GS
Apple High-Speed SCSI card
90 mb Bernoulli hard drive
System 6.0.1
Three things I can think of to check:
One possibility is DMA compatibility. If your memory card is not DMA
compatible, then switch 1 on the Apple HS SCSI card should be open (up).
Another possibility I guess is a SCSI ID conflict. The Apple HS SCSI card's ID
at the factory is set to 7. Here are the Apple HS SCSI card switch
combinations:
note1: Switch 1 controls DMA; open (up) turns DMA off
note2: Switches 2-4 control SCSI card ID
note3: 'U' means open (up), 'D' means closed (down),
'z' means Set for correct DMA (see note1)
SWITCH: 1234 1234 1234 1234 1234 1234 1234 1234
SETTING: zUUU zUUD zUDU zUDD zDUU zDUD zDDU zDDD
CARD ID: 0 1 2 3 4 5 6 7
Third, the scsi chain needs termination power to work properly. This is
different from termination. Both are required for a properly functioning scsi
chain. It is possible that neither the Bernoulli drive nor the Apple HS SCSI
card is supplying termination power. If this is the case, and there is no
other device on the scsi chain to supply said power, it probably won't work.
There is a modification (requires soldering skills) to the Apple HS SCSI card
to make it supply termination power.
By: Jack Countryman IAC
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