30 Jun
2005
30 Jun
'05
12:39 p.m.
Has anyone here successfully interfaced a SASI device to a PC at the
hardware level?
I've got a few classic systems which use SASI (or not-quite-SCSI)
controllers to talk to SASI-ST506 bridge boards and from there to ST506
type drives.
I was under the impression that SASI was sufficiently close to SCSI that
a SCSI interface could talk to a SASI device given the right software. It
would probably make things simpler if the SASI device and the controller
were the only things on the bus.
As has been documented many times in the past here, an ST506 drive has a
pretty tight relationship with its controller, and so hooking up the
drive to a different controller (say MFM controller in a PC) causes all
sorts of problems when it comes to backup.
Hence driving the SASI side of things (and preserving the drive/bridge
board relationship) would seem like a sensible move when it came to
backing up data. In theory data could then be restored to a replacement
drive if/when the original dies via the same method.
Agreed.
Presumably inventing a simple SASI board to hang off a PC parallel port
(say) is a lot easier than mucking around with the equivalent for floppy
drives - or is the data rate still likely too low to cause timeout
problems within the bridge board's firmware?
I am pretty sure you can drive it as slowly as you like. All the bridge
boards I've seen have intenral buffer memory, certainly enough for one
block.
I've got several Acorn, Torch and RML machines which use bridge boards
FWIW the Torch XXX uses a SCSI interface chip on the mainboard, and I
thought the drive bus was SCSI on that machine.
-tony