RK02

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RK02/RK03
Manufacturer: Diablo Systems
Capacity: 1.22 Mbytes (RK02)
2.45 Mbytes (RK03)
Drive Controller(s): RK8E (Omnibus)
RK11-C (UNIBUS)
Revolutions Per Minute: 1500
Total Surfaces: 2
Sectors Per Track: 16 (RK8E)
12 (RK11)
Words Per Sector: 128 (RK02-RK11)
256 (RK03-RK11)
Tracks Per Inch: 100
Density: 1100 bpi(RK02)
2200 bpi (RK03)
Recording Method: Double Frequency
Transfer Rate: 22.2 μsec/word (RK02-RK11)
11.1 μsec/word (RK03-RK11)


The RK02 and RK03 were moving-head removable-pack magnetic disk drives, sold by DEC, but designed and manufactured by Diablo Systems. They were inspired by the IBM 2315 drive and pack.

The original RK02 (Diablo Model 30) was soon joined by the RK03 (Diablo Model 31), a double-density model which held twice as much data.

The pack contained a platter 14 inches in diameter, coated with iron oxide. Since the disk was hard sectored, platters used in the PDP-8 were physically incompatible with those used in the PDP-11, although the drives themselves were completely identical for both.

Other specifications

RK03 drives
  • Data tracks - 203 (nominally 200 plus 3 spares)
  • Average access time - 70 msec
  • Time for 1/2 revolution - 20 msec
  • One track seek - 15 msec
  • Average seek - 70 msec
  • Maximum seek - 135 msec
  • Physical size - 19" W x 10.5" H x 26.0" L
  • Weight - 43 pounds (basic Diablo drive)

External links