Re: Help with SCSI-2

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

Laer Haider <lkhaider@concentric.net> wrote:

> I received a free Seagate ST-3610N 535MB SCSI-2 HDD (technical details
> follow).  I was hoping to use it on my IIgs as a replacement HD
> (faster and bigger), but ran into some trouble.

[Details snipped]

This drive certainly should work on the IIgs, with either a RamFast or
Apple SCSI card.

There are some newer drives (notably the Quantum Fireball) which do not
work with a RamFast, because they require a specific SCSI feature which
is not supported by the RamFast (but is supported by the Apple cards).

I doubt this is the problem here, because these drives don't work at all
if you try to use them with a RamFast.

The most likely cause is improper SCSI termination.  There should be one
terminator (either passive or active) at the end of the drive chain.

There might also be some odd conflict with other devices on the bus.
Some weird SCSI problems can be solved by rearranging the order of
devices, removing other devices, or by over-terminating or
under-terminating the bus.

Do you know anyone who has an Apple SCSI card?  It would be interesting
to try the drive on that, and see if it works, or at least to see if
there are different symptoms.

> Am I missing something here?  Are SCSI-2 devices not compatible with
> the RamFAST?  Not compatible with SCSI-1 devices?  The Apple IIgs?  Is
> there some hardware hack I can do?  Some driver I can use?

In general, SCSI-2 devices are compatible with SCSI-1 devices.  The main
difference between SCSI-1 and SCSI-2 for hard drives is that SCSI-2
drives implement a more standard command set, and that SCSI-2 supports
"Fast SCSI" (an optional feature which is not supported on an Apple II
anyway).

SCSI-2 also standardised many other device types (e.g. CD-ROM drives).

-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand