Re: High Speed SCSI and ProDOS

[dempson@actrix.gen.nz (David Empson)]

Phil Abel <ttsh35a@removethisfornospam.prodigy.net> wrote:

> "Just" upgraded from a Rev C to a HS SCSI card.  While GS/OS recognizes all
> my drives just fine, I can not get ProDOS 8 to recognize any of them.  When
> I boot the SCSI slot directly I get a "SCSI BOOT ERROR".  I don't have any
> SCSI ID conflicts or anything.  I tried with DMA on and off and it didn't
> change anything.  My other cards are a TWGS, GS Ram 4 w 4MB, and SuperSonic.
> I seem to recall reading somewhere that the HS SCSI won't read a ProDOS
> drive if you have multiple partitions?  Is this the case?  All the drives I
> tested had 2 or more partitions.  If this is indeed teh case, what if I set
> up a drive with 1 Prodos partition and 1 or more HFS partitions-- will I be
> able to boot from ProDOS then?

As long as your first partition is ProDOS, the High-Speed SCSI card
_should_ work fine, and should be able to boot.

I have a total of 11 partitions on my 850 MB hard drive.  The first six
are ProDOS (32 MB each), the next four are HFS, and the last is ProDOS.
Depending on what other disk drives I have enabled in the machine, I can
see at least four and as many as seven of the ProDOS partitions while in
ProDOS 8.

The High-Speed SCSI card firmware will support a maximum of 110
partitions, and ignores everything except ProDOS partitions.  ProDOS-8
2.0 or later will only provide access to a maximum of 12 partitions, and
then only if you have no other disk drives connected and/or no enabled
disk controller cards apart from the SCSI card itself.

It sounds like you have some kind of hardware problem.  I doubt it is
the firmware on the card.  The most likely explanation is that your SCSI
termination isn't set up correctly.  Termination problems can have all
sorts of odd symptoms, including failure to boot but no apparent problem
accessing the drive while booted from floppy, and/or different behaviour
between the firmware and the GS/OS drivers.

A significant difference between the original and High-Speed Apple SCSI
cards is that the former has no termination, and therefore requires a
pass-through terminator between the card and the first peripheral if you
are connecting more than one peripheral.  The High-Speed card is
terminated, so you must only have one other terminator, in/after the
last peripheral on the SCSI chain.

A related issue is the supply of termination power: the original Apple
card didn't do this, and the neither did the high-speed card until Apple
modified it later in its life cycle.  Ideally, you should have a drive
which supplies termination power itself, but failing that may need to
modify the card to supply termination power.