RXV21 question

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Sun Apr 6 13:06:14 2003

> OK, this may be obvious to the experts here, but I haven't a clue: can a DEC
> RXV21 RX01 / RX02 floppy controller be used with non-DEC floppy drives, using
> the standard DEC RT11 driver? By non-DEC I mean ordinary SSSD or SSDD Shugart,
> Siemens, or Qume 8" floppy drives.

Anything is _possible_ (apart from ski-ing through a revolving door :-)),
but it may not be easy. And using an RX211 or RXV21 or RX8 or ... with
normal drives is certainly not easy.

The reason is that these cards are _not_ floppy controllers. They're bus
interfaces between Unibus/Qbus/Omnibus and a serial link to the drive.
The actual controller is inside the drive chassis -- a board of AMD29xx
bit-slice chips in the RX02 and a board of TTL + microcode PROMs in the
RX01. This controller is responsible for positioning the heads, finding
sectors, doing the CRC, and so on.

Third-party contollers (mostly Qbus) that linked SA800 drives to DEC
machines had a fair amount of logic on the card, often including a pair
of 2901 ALUs and a 2910 sequencer.

-tony
Received on Sun Apr 06 2003 - 13:06:14 BST