23 Jul
2004
23 Jul
'04
3:31 p.m.
On Thu, Jul 22, 2004 at 11:38:19AM -0400, Bill Pechter wrote:
DEC modified the SMD signals on the RM02/RM03/RM05 to
make them
slightly different from standard SMD versions and they also used
the CDC high altitude heads to reduce crashes.
I didn't know about the high altitude heads. That's an interesting
tidbit.
RM02/RM03 is 80mb unformatted 67 formatted. CDC sold
the drive
which could be set to many different sector sizes and sector counts
per cyl.
So the DEC was 31 or 32 (IIRC) sectors of 512 bytes per track.
CDC topped out with 33 sectors...
A-ha! That makes perfect sense. With a bit of googling (RM02, RM03,
9762 and cylinder), the first hit is http://www.inwap.com/pdp10/usenet/disks
In the article, among other disk sizes, the RM02/RM03 is 823 cyls, 5 heads,
32 sectors/track - 67,420,160 bytes (33 s.p.t is 69,527,040, meaning that
there must be a bit of overhead compared to the 80MB unformatted capacity).
-ethan
--
Ethan Dicks, A-130-S Current South Pole Weather at 24-Jul-2004 03:10 Z
South Pole Station
PSC 468 Box 400 Temp -83.8 F (-64.4 C) Windchill -133.1 F (-91.8 C)
APO AP 96598 Wind 18.5 kts Grid 004 Barometer 664.7 mb (11208. ft)
Ethan.Dicks(a)amanda.spole.gov http://penguincentral.com/penguincentral.html