31 Oct
1999
31 Oct
'99
7:52 a.m.
On Sun, 31 Oct 1999, Tony Duell wrote:
I'd always assumed (without much evidence) that
electrically it was
pretty similar to the PC ISA bus. Of course BIOS extension ROMs on I/O
cards aren't going to work (different CPU for one thing).
I know that some cards will work in both the Apollo and normal PCs..
Tony, you've hit the nail on the head. The Apollo ISA bus is a real ISA
bus.
However, most ISA cards will not work in the machine for one of a number
of reasons:
- The Apollo cannot use any BIOS extension ROMs due to it not having the
PC BIOS to extend, and because it's architecturally completely dissimilar
to a PC (Motorola 68k CPU being byte-backward from x86).
- There is no OS support. DOMAIN/OS has a very limited view of the world
with respect to hardware device drivers.
Theoretically it would be possible to make any arbitrary ISA card work in
an Apollo if one were to write his own device drivers and software to use
that driver. This driver would have to use no calls at all to the BIOS
extension ROM, which as I understand can be tricky to work around as even
if you get programming information from the manufacturer for the card, it
will often not tell you where, for example, the hardware registers live
beyond those presented by the onboard BIOS.
Anyway.
Oh, yes, and the WD7000/ASE found in Apollo workstations (only supported
in a few late models) is a "Three-way peripheral controller" bearing only
slight resemblance to the Intel PC product, the WD7000/FASST SCSI
controller.
The /ASE has floppy, ESDI, and SCSI interfaces. Don't expect to be able to
boot the Apollo from a SCSI disk, or even to use one at all unless you are
running DOMAIN/OS at 10.3.5 or later. The SCSI interface seems only to be
well-supported for tape devices (two in particular, an Archive 60 MB QIC
unit, and the Exabyte 8200).
ok
r.