SASI and XT/IDE info

Jules Richardson julesrichardsonuk at
Tue Nov 27 11:52:39 CST 2007

Roy J. Tellason wrote:
> On Monday 26 November 2007 20:17, Ethan Dicks wrote:
>> I've often mused about investigating the 90x0 firmware to see if it's
>> possible/reasonable to make the "DOS Board" speak SCSI rather than SASI,
>> but that's one of those long-term projects that just hasn't come up in
>> the queue yet.
> How much of a difference is there between the two,  really?

I think there was an extra protocol phase added for SCSI, plus parity support 
crept in at some point, as did a few extra commands (e.g. 'basic' stuff like 
Inquiry). I don't think there's a clear definition between SCSI and SASI 
though, as some early devices calling themselves SCSI are pretty broken by 
modern definitions of the standard.

 From scratch, it'd be possible to make a dual-purpose SCSI/SASI interface I 
think - but taking someone else's SASI interface and hacking on the extra 
logic necessary for SCSI might be more tricky.

Chris - you probably have something quite unique there. Whilst things calling 
themselves SASI interfaces are common in old 8-bitters, this is the first I've 
heard of one for the PC...



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