SASI and XT/IDE info

Roy J. Tellason rtellason at
Tue Nov 27 13:59:15 CST 2007

On Tuesday 27 November 2007 12:52, Jules Richardson wrote:
> 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.

Mostly I was thinking about the fact that my BigBoard II has a SASI port on 
it,  and how I have this whole *pile* of "small" SCSI drives (2G mostly) and 
how much room that'd be on one of those.

All I'd need is to add an EPROM with some code in it to boot the thing,  and I 
could do just about anything I wanted to from there.   Get the right CRC in 
there and the BBII rom hands control off to it automatically...    :-)

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ablest -- form of life in this section of space,  a critter that can
be killed but can't be tamed.  --Robert A. Heinlein, "The Puppet Masters"
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M Dakin

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