🚀 go-pugleaf

In article <DGRAY.92Nov8104036@menudo.uh.edu>, dgray@menudo.uh.edu (Dennis Gray Jr.) writes:
> Does this mean that you can use any MFM drive in a micro vax?  (how
> about a vax station?)  If this is true, is there a MAX # of
> heads/cyls?

  Nope. The earlier controllers (RQDX1, RQDX2) did various "unnatural acts"
(illegal seeks, selecting nonexistant heads, etc.) to guess what drive type
was attached. Even a drive with the same geometry might not work, depending
on the response it gives to such illegal commands. That's why the RD53 has
the R7 jumper - to change it's behavior to make it distinguishable from the
earlier drives.

  The RQDX3 can support other geometries, but you have to enter the size of
all of the MSCP regions and the controller does no checking of the values,
so you can (for example) have a drive that acts fine until the first time it
does a bad block replacement, and then becomes unusable.

  In general, it's best to stick with the recognized drives (RD51=ST412,
RD52=Q540/3046/5540(heh!), RD53=1325/1335, RD54=2190) or to get a new con-
troller and drive using some other interface (ESDI/SCSI) if you need more
speed/capacity.

	Terry Kennedy		Operations Manager, Academic Computing
	terry@spcvxa.bitnet	St. Peter's College, Jersey City, NJ USA
	terry@spcvxa.spc.edu	+1 201 915 9381