🚀 go-pugleaf

In article <8691@pitt.UUCP>, jcd@pitt.UUCP (Jim Durham) writes:
>    RD53's are Micropolis drives. There are other drives, like Maxtors
>    that have the same geometry as the Micropolis, but the DEC "Customer
>    Formatter" will not touch them. I understand that "real" RD52s and RD53s
>    have a "descriptor block" somewhere on the drive that tells the formatter
>    that this is a "real" RD and allows it to format the drive.

  There are a number of issues here. The earlier DEC controllers (RQDX1 and 2)
needed to determine the drive type at every power-up, so they need to be able
to find out the drive type rapidly. Thus, the DEC drives supported on the 1
and 2 have unique characteristics. That's what R7 on the RD53 is for - to tell
the RQDX2 that it's an RD53 instead of an RD52.

  The RQDX3 (and integrated controller in a 2000) write the geometry infor-
mation on the drive when it is formatted. Thus, they can accomodate non-DEC
drives (unlike the 1 and 2). I believe the formatter only asks you "which
DEC drive do you have". You can specify drive geometry (in the RQDX3 inter-
nal formatter), but you need more numbers than you can easily get in order
to define the MSCP regions.

	Terry Kennedy		Operations Manager, Academic Computing
	terry@spcvxa.bitnet	St. Peter's College, US
	terry@spcvxa.spc.edu	(201) 915-9381