RL01 disk drive

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Manufacturer: Digital Equipment Corporation
Drive Controller(s): RL11 (UNIBUS)
Capacity: 5.2 Mbytes (formatted)
Transfer Rate: 512 Kbytes/sec
3.9 usec/word (peak)
Average Access Time: 67.5 msec
Revolutions Per Minute: 2400
1/2 Revolution Time: 12.5 msec
One Track Seek Time: 15 msec
Average Seek Time: 55 msec
Maximum Seek Time: 100 msec
Head Switching Time: 8 msec (maximum)
Total Surfaces: 2
Tracks Per Surface: 256
Sectors Per Track: 40
Words Per Sector: 128
Tracks Per Inch: 125
Density: 3725 bpi (maximum)
Recording Method: Modified Frequency Modulation (MFM)
Start Time: 40 seconds
Stop Time: 30 seconds
Physical Size: 19" W x 10-1/2" H x 25" L
Weight: 55 pounds
Power Consumption: 160W (running); 550 VA (starting)
An RL01

The RL01 is a 5MiB, single platter, removable pack disk drive introduced in 1976 by Digital Equipment Corporation. It used an IBM 5440 type pack, as used on the IBM System/3.

To keep the heads properly aligned on the tracks, it used a servo system driven by servo data written on the pack (along with sector headers) at the factory; packs cannnot be low-level re-formatted in the field.

RL01 drive

Early versions of the drive included a set of brushes that swing out over the platter on start-up; these were deleted in later versions.

The QBUS controllers are the RLV11 and RLV12, the latter being the Q22 version.

The RL02 is a higher density version, with twice as many tracks.