15 Dec
2013
15 Dec
'13
11:58 a.m.
In terms of DEC, I think the Diablo 31 worked well on the RK11-C, but there
might have been a trick to using it on the RK11-D.
Yes. The problem is the drive sleect lines. The Diablo uses 1-of-n select
(that is, there are 4 lines, one is asserted to select each drive, like
a Shugart floppy drive interfce). The RK05 can use either 1-of-n sleect
or binray sleect (where 3 of the sleect lines carry a bianry code to
sleect one of 8 drives on the same cable).
The RK11-C uses 1-of-n sleect and will work with either drive. The RK11-D
uses bianry slect and works with the RK05 only. The fix is to add a
decoder IC (liek a 7442)
I think Plessey made a 2-plater drive, one fixed, the other removeable,
that had a DIablo-like interface. They also copied the RK11-D. The cable
to link the drive to the contorller had a little bit of electronics on
the PCB that pluggedi nto the controller bnckplane. I assume this was a
decoder.for the drive select lines.
I don't remember having any problems using DEC
packs on the Diablo drive.
DEC RK02s and RK03s were Diabloes (normal and high density models). FAIK
the RK05 was designed ot use the same pack.
Was the RK04 (which AFIAK never existed) going to be the low-density
versio nfo the RK05?
-tony