Re: SCSI Card

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

Wayne Stewart <waynes@intergate.ca> wrote:

> Bryan Parkoff wrote:
> > 
> >     Which is better to use Apple SCSI card rev A or rev C for both IIgs ROM
> > 01 + 03.  What about Apple High Speed SCSI card for both ROM 01 + 03?
> 
> The Rev C is better in any IIgs, earlier revs won't work with GSOS. 

Note that it is just the firmware - you can upgrade the ROM in an older
card to revision C (341-0437-A).

> The Hi-Speed SCSI card would be better yet. It's a little faster

A "little" faster?  It is noticeably faster in ProDOS-8, and a lot
faster in GS/OS.

The RamFast SCSI card is a lot faster than the Apple High-Speed SCSI
card if you are running ProDOS-8, but isn't much better than the Apple
card in GS/OS.  (If anything, the theoretical peak performance of the
Apple card will beat the RamFast, but you are unlikely to achieve this
without specially written software.)

> and allows a much wider selection of CD drives. It's also much better with
> any removable media drives.

These issues both only affect the operation of the Apple cards in
ProDOS-8 (and when booting from the SCSI card), at which times you are
dependent on the firmware provided by the card.

The original Apple SCSI card doesn't know about removable hard drives,
so if you swap cartridges in a Zip or SyQuest and don't reboot, it will
continue to use the partition map from the original cartridge,
potentially destroying the contents of the new cartridge.  It didn't
support CD-ROM drives until the revision C firmware.

The High-Speed card firmware has full support for removable hard drives
and may support a wider range of CD-ROM drives.

GS/OS uses native drivers which support both cards, so the firmware
capabilities are irrelevant.  While you are in GS/OS, you can use the
same peripherals with both cards with the same behaviour (except for the
difference in performance between the cards).

-- 
David Empson
dempson@actrix.gen.nz