> Here is a pic of the actual chip... can the version be determined from this?
No, anything could be written to that chip. Do a 'version scsi.device', maybe other folks here with an A590/2091 are kind enough to post their ROM / device version numbers for comparison.
> What I'm trying to do is determine what SCSI HDD I can replace the original XT HDD with. I have a Quantum 4550S SCSI 4.5 GB HDD 80 Pin that I would like to drop in.
Sounds like an SCA drive, so you'd need an SCA -> 50 pin adapter. If you're not planning to use a longer bus, you can probably get away with a simple adapter w/o terminating option, otherwise you'll need a better one with terminator.
> Do I need to still use the power connector in the A590 for the SCSI drive or is that for the XT drive only?
That power connector will do fine - if the drive has one (see below).
> This next question is a doozy.... how can I transfer all the data from the XT drive to the SCSI HDD?
Well, it's either backup/restore or hook up both simultaneously (with a Y-adapter for power).
> Also, can anyone confirm that the Quantum Atlas II 4550S / PN HN45J011 is really an 80 Pin drive? There is so much conflicting info on the web.
Count the pins. ;-) If there's a power connector on the drive, it's wide SCSI (68 pin), so you'd need an adapter for that. 80 pin SCA includes power, so there's no separate connector.
