23 Sep
2021
23 Sep
'21
7:50 p.m.
My notes (from sources unknown) say (of the ML11A):
solid-state (ram) disk; 2MB/s xfer
1-31 arrays of 512 or 2048 blocks ea
using 11/70 MK11 (MOS) memory
looked like RS03/RS04 to s/w
Ok, that makes sense.
http://gunkies.org/wiki/RS03/04_disk_drive
says about *REAL* RS03/04 drives:
"basic format was 18-bit words
(for use in PDP-10 and PDP-15 machines)"
But I doubt that anyone would care to replicate THAT feature
(throwing away two bits of each word) on a PDP-11 option!
Well, that would otherwise have been used for Massbus parity. The number
of bits on the drive stayed the same, it's just that the formatter would
either format the disk for 512 or 576, then use the top two bits either
for parity or the last 2 data bits.
The other fun question that I have to figure out is can an RM80 be run
in 18 bit mode. I'm guessing it can as it uses the same Massbus
formatter as the RM02/03/05. Need to roll that thing out of my son's
closet when he moves out and see what happens...
C