> Anyway do the MFM controllers in PROs have the same hard-coded drive model
>restrictions as their Qbus big brothers, like the RQDXn family?
On a PRO, the MFM hard drive is ID'd by the number of heads and
number of cylinders. If you look at, for example, DW.MAC on a RT-11
distribution kit, you'll find the table quite easily. You can add
your own devices to the table - just keep in mind that it has to
be in ascending order by heads, and then ascending order by
cylinders.
OK, the above is a bit of an oversimplification - if the drive in
question happens to be a RD50, the drive might be damaged by the
seek test that counts the number of cylinders. So RD50's
are identified by a bit in the status/init register, and not
by the seek test.
The PRO's MFM controller only allows 3 bits for the head ID and 10
bits for the cylinder ID, so you can only use drives up to 8
heads and 1024 cylinders (aka the RD53).
--
Tim Shoppa Email: shoppa_at_trailing-edge.com
Trailing Edge Technology WWW: http://www.trailing-edge.com/
7328 Bradley Blvd Voice: 301-767-5917
Bethesda, MD, USA 20817 Fax: 301-767-5927
Received on Wed Jul 28 1999 - 09:37:57 BST