7 Jul
2006
7 Jul
'06
10:59 a.m.
Jules Richardson wrote:
Thought for the morning - it'd be nice if the
hardware was switchable
between SCSI and SASI. In a moment I'll dig out the docs I have for the
Omti 5x00, Adaptec ACB4000, Xebec (umm, 1452 or something like that) and
the Emulex boards.
Right, low-down on the various boards:
OMTI 5000 series: Manual calls the interface "SCSI/SASI" - from the wording it
was current before SCSI was actually a recognised standard, but they've done
their best to cope with the forthcoming spec. The board does support parity
detection/generation (can be disabled via a jumper) and the device ID is
selectable. The board *does not* support disconnect/reconnect, message out, or
re-select. Single-host environment only.
Bus signals used: D0-7, parity, BSY-, ACK-, RST-, MSG-, SEL-, C-/D, REQ-, I-/O.
Drive geometry is controlled by an "Assign disk parameters" command (0xC2) and
is *not* persistent across power cycles.
Bytes/sector is jumper-selectable to 128, 256, 512 or 1024 bps.
Xebec S1410: Manual calls the interface SASI. No support for parity generation
or checking on this one. Device ID is selectable by cutting PCB traces (yuck).
Bus signals used: D0-7, BSY-, ACK-, RST-, MSG-, SEL-, C-/D, REQ-, I-/O.
Drive geometry is controlled by an "Initialize drive characteristics" command
(0x0C) and is *not* persistent across power cycles.
Bytes/sector is jumper-selectable to either 256 or 512 bps.
Adaptec ACB4000: Manual uses the term 'SCSI' exclusively. Parity
generation/detection is not supported, however. The board doesn't support
disconnect/reconnect, or arbitration. Single-host environment only.
Bus signals used: D0-7, BSY-, ACK-, ATN- RST-, MSG-, SEL-, C-/D, REQ-, I-/O.
Drive geometry is controlled by a mode select command (0x15) and *is*
persistent across power cycles; at format time the board stores the drive
geometry at block 0 (and offsets normal drive accesses by 1 block) - when the
board is power cycled it automatically reads this geometry back from the drive.
Bytes/sector is selectable to 256, 512 or 1024 bps.
Emulex: I don't have any info on their boards, just the boards themselves.
Will check bitsavers at some point.
The problem here lies with the Adaptec board - it uses the ATN line found in
full-blown SCSI, whereas all the other bridge boards don't. At least on this
side of the pond, it's a common board too that gets used in a lot of classic
hardware; it'd be a shame if it was unsupportable :-(
cheers
Jules