7 Jan
2015
7 Jan
'15
8:11 p.m.
I nave 2 RK11-C backplanes, a Diablo drive, and a Plessey controller here
if anyone is interested. Feel free to make me an offer off list.
On Wed, Jan 7, 2015 at 11:44 AM, tony duell <ard at p850ug1.demon.co.uk> wrote:
The standard RK8E do a select using just one pin, meaning you can have
at most 4 drives on the system.
The RK11 have a binary unit number encoding, meaning you can have 8
drives.
The RK11-D (and I guess RKV11) use binary encoding on the select lines, so
up to
8 drives on the cable. The RK11-C uses 1-of-n encoding (like the RK8E) and
allows
for 4 drives per cable. But the RK11-C has 2 cable connectors, so you can
have
8 drives on it.
The older RK02 and RK03 drives (Diablo model 30) used 1-of-n encoding only,
and will not directly work with the RK11-D. I seem to remember a Plessey
clone
of the RK11-D which had an interface board in the disk cable slot which
had a
decoder IC on it to allow for 1-of-n selects.
More fun is that the same pins were used for both
binary and 1ofN
selection. I don't remember how on earth this was detected/handled by
the drives, as I don't remember anything beyond the unit setting rotary
switch on one of the boards of the RK05.
There was a pin on the drive interface connector which if high enabled
1-of-n
selects (it was normally pulled high by the terminator). If pulled low
(done
by an RK11-D controller) the drive used binary selects.
-tony