22 Nov
2005
22 Nov
'05
10:16 p.m.
Tony Duell wrote:
Isn't SASI just single target though? (I'd forgotten this, I was thinking that
it was multiple target like SCSI just without all the device reservation like
SCSI)
So if the board (despite Acorn calling it SCSI) is really just SASI (or maybe
if it started life as a SASI project) then it could explain why the software
never addressed more than one target device.
Either that or Acorn were rather short-sighted in their software, but they
weren't normally known for this (typically, if the hardware would do it they
seemed to think that someone would actually want to do it).
Maybe it comes down to code size and there just wasn't the room in the ADFS
ROM for the device selection code (assuming that Acorn's board contains the
necessary SCSI features anyway - I think you likely need /ATN to do device
selection?)
You made me realise that I need to archive the ROMs from the E01 I have in the
cupboard - I've only got E01S ROM dumps on this 'ere PC (at least they're
512Kbit). I've never had an E01S, but I do get stray ROMs amongst Acorn finds
occasionally, which is where these will have come from. Incidentally I have a
"Version A" ROM and a "Version 1" ROM; why Acorn named one with a
letter and
one with a number I don't know (they are different in content)
cheers
Jules
I'd
forgotten about that; in ADFS-land, ADFS knew nothing about device IDs -
everything was ID 0 and so the host adapter could still only have one device
How stupid! I wonder why they did that (after all, they allowed for
multiple floppy drives on the same controller). It's almsot as stupid as
POS haeving 2 storage devices (one floppy, one winchester) hard-coded
into the OS. connected up
to it. Maybe that was fixed for the Filestore's firmware though,
as it always seemed like a silly omission.
According to the docs, the E01S (with the host adapter on the mainboard)
supported up to 4 SCSI drives. Now, the ROM is different between the E01
and E01S (if only because the former has a pair of 27256s, the latter a
single 27512)