> A better solution is what's already being discussed: an MSCP server on a
> Qbus card. While I'd personally prefer SCSI to IDE, the ability to put any

Ummm...Actually SCSI vs. IDE argument goes away, in this case, because:
1) Qbus can't even hope to keep up with most any off the shelf EIDE drive made in the last
few years.
2) Using a processor to talk to the IDE, for the VAX, is tantamount to the SCSI
intelligent controller concept.

I.e. if I were really bent on it (and I'm not) I could make a controller to which you
could connect an IDE drive.  On the other side, I could talk out SCSI, then you could hook
it to any old SCSI bus. Thus you could us an IDE drive in any SCSI system.

The point here is implement MSCP which will give this board life under most any VAX OS.
Additionally, because it will be an intelligent controller, it will take the load off an
already very slow CPU.

The dumb IDE Qbus board is a great idea, but terribly inefficient, for a VAX, due to the
high cost to the CPU for processing.  On the flip, at least it's something!

> old disk i can find anywhere right now into my VAX is a cool things to have.
> while some of us, myself included, are lucky enough to have a sufficient
> supply of the CMD, emulex, and few other qbus/scsi cards, most of the users
> here and elsewhere probably arent.

And when that supply runs out for us...  I'm fortunate enough to have 2 RD54s, but I know
they are not going to live forever, and I tend to limit usage of my VAX for that reason.
Besides...150Megs is becoming super small these days.

> I don't know if a Z80 can keep up with doing MSCP at qbus speeds. Granted,
> IDE disks alone arent any faster than the qbus, but with lots of buffering,
> multiple disks, etc, i think a z80 would be swamped. how about a strongarm
> or a 68k? we can be gratuitous with buffering and such these days, too..

Yes, I considered this.  A regular Z80 at 4Mhz is probably too slow.  I considered a Z180
at 10-20Mhz, but though it can access 1 Meg, it's still an 8 bit bus and I really don't
seeing latching/buffering a 16->8bit bus as a good solution, considering chip
alternatives.  The Z380 has a 16bit bus and can access 4gig of RAM flat (no offset) and is
a serious contender.   I'm seriously considering a 386 custom solution too, if for no
other reason, the wealth of design info on it.  I want to work with what I'm already
familiar.

In the end, it all depends on how motivated I can get myself :-)

jam