RM02/03 disk drive

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RM02/RM03
Manufacturer: Digital Equipment Corporation
Drive Controller(s): RH10 (PDP-10)
RH20 (KL10)
RH11 (UNIBUS)
RH70 (PDP-11/70)
RH780 (VAX-11/780)
RH750 (VAX-11/750)
Capacity: 67 Mbytes
Transfer Rate: 2.48 μsec/word (RM02/16-bit)
2.79 μsec/word (RM02/18-bit)
1.65 μsec/word (RM03/16-bit)
1.86 μsec/word (RM03/18-bit)
Average Access Time: 42.5 msec (RM02)
38.3 msec (RM03)
Revolutions Per Minute: 2400 (RM02)
3600 (RM03)
1/2 Revolution Time: 25.9 msec (RM02)
17.3 msec (RM03)
One Track Seek Time: 6 msec
Average Seek Time: 30 msec
Maximum Seek Time: 55 msec
Total Surfaces: 6 (5 data, 1 servo)
Tracks Per Surface: 823
Sectors Per Track: 30 (18-bit words)
32 (16-bit words)
Words Per Sector: 256
Recording Method: MFM
Physical Size: 33" W x 39" H x ??" L
Weight: 430 pounds


The RM02 and RM03 were MASSBUS multi-platter large moving-head disk pack drives. They were effectively identical, except that the RM03 rotated faster (3600 RPM, versus 2400 RPM for the RM02). Both supported both 15-bit and 18-bit words; user data is protected by a 32-bit ECC per sector.

RM0x drives are dual-ported, allowing any drive to be attached to two different controllers. Generally a maximum of 8 drives were supported per device controller.

The RM02 provided 806 KB/s transfers; the RM03 had 1200 KB/s transfer.