RK05 disk drive

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Manufacturer: Digital Equipment Corporation
Drive Controller(s): RK8E (Omnibus)
Capacity: 2.45 Mbytes (most versions)
Transfer Rate: 102 Kword/sec (RK8E)
90.1 Kword/sec (RK11)
Average Access Time: 70 msec
Revolutions Per Minute: 1500
1/2 Revolution Time: 20 msec
One Track Seek Time: 10 msec
Average Seek Time: 50 msec
Maximum Seek Time: 85 msec
Total Surfaces: 2
Tracks Per Surface: 203 (nominally 200 plus 3 spares; many systems used all 203, as reliability was high)
Sectors Per Track: 16 (RK8E)
12 (RK11)
Words Per Sector: 256
Tracks Per Inch: 100
Density: 2200 bpi
Recording Method: Double Frequency NRZ
Physical Size: 19" W x 10.5" H x 26.5" L
Weight: 110 pounds
Power Consumption: 230 VA (running); 1150 VA (starting, 2 sec)
An RK05 with the door open, showing the removable pack (white plastic)

The RK05 was moving-head magnetic storage disk drive, most versions of which used removable packs. They were designed and manufactured by DEC, and based on, but not completely compatible with, the earlier RK02 and RK03 drives (which were sold by DEC, but not manufactured by them), which in turn were inspired by the IBM 2315 drive and pack.

The pack contained a platter 14 inches in diameter, coated with iron oxide. Since the disk was hard sectored (using narrow slots cut through a projecting ring in the hub), packs used in the PDP-8 were physically incompatible with those used in the PDP-11, although the drives themselves were completely identical for both.

An RK05 with a cartridge loaded

The controller interface on the RK05 was mostly compatible with the earlier RK02/RK03, although it used a different 'drive select' mechanism, which allowed an RK11-D controller to support up to 8 RK05 drives on a single drive bus, as opposed to only 4 per bus with the earlier RK02/03 and RK11-C system. The packs were compatible.

RK05 models

An RK05 head
  • RK05E - a version which contained many reliability enhancements
  • RK05J - the final version
  • RK05F - a version using a permanently installed platter, which allowed it to operate at twice the track density of the standard RK05, doubling the capacity of the drive; a single RK05F emulated two normal RK05 drives

Mounting slides

The mounting slide DEC used was the General Devices 'Chassis Trak' C-230-S-122 (22"), which are still available (e.g. from Newark). They're somewhat pricey - the -124 (24") is sometimes slightly cheaper, and can easily be modified to fit an H960 rack, by drilling two extra holes.

External links