RA60 Disk Drive

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Manufacturer: Digital Equipment Corporation
Year Introduced: June, 1982
Drive Controller(s): all SDI controllers
Capacity: 205 Mbytes (16-bit mode, formatted)
208 Mbytes (18-bit mode, formatted)
Transfer Rate: 1.3 Mbytes/sec
Average Access Time: 50.3 msec
Revolutions per Minute: 3600
1/2 Revolution Time: 8.3 msec
One Track Seek Time: 6.7 msec
Average Seek Time: 41.7 msec
Maximum Seek Time: 75 msec
Total Surfaces: 6
Number of Heads: 6
Tracks per Surface: 1,588
Sectors per Track: 38 (18-bit word mode)
42 (16-bit word mode)
Bytes per Sector: 512 (16-bit word mode)
576 (16-bit word mode)
Tracks per Inch: 779
Density: 9,668
Start Time: 60 secs (max)
Stop Time: 40 secs (max)
Physical Size: 26cm x 44cm x 85cm
Weight: 155 lbs (approx)
Power Consumption: 780 watts

An open RA60

The RA60 Disk Drive is a DEC SDI removable-pack disk drive, introduced in 1982; it could support either 16- or 18-bit words. It is the only removable-media drive in the RAxx group of drives; the others (RA70, etc) are all non-removable-media disk drives. It is member of the Digital Storage Architecture family.

It uses the RA60-P pack, which has a five platters, with six data surfaces; the two end platters are purely protective. Track servo information is pre-recorded on the data surfaces; the servo information is recorded at manufacturing time.

The RA60 can also be connected in a dual-port arrangement, permitting its use by two controllers.

Quote from the combined DEC RA60/RA80/RA81 1982 sales brochure:

The RA60 is the industry's highest capacity and lowest price-per-megabyte rack mounted, removable media disk. With 205 megabytes of user formatted capacity, 615 megabytes are available in a 42-inch high cabinet - 50% more than any other removable media product. The RA60 provides 205 megabytes of removable media flexibility for $15,000.

Some DEC marketing material refers to the RA60 as a 'Winchester' drive; strictly speaking, this is not completely accurate. It does use some aspects of Winchester drives, such as the use of pre-recorded servo information, but it does not have a sealed HDA, which many regard as the key innovation in Winchester drives.

4.3 BSD disktab

ra60|RA60|DEC RA60 Removable:\

Further reading

  • RA60 Disk Drive User Guide (EK-0RA60-UG-001 - not available online)
  • RA60 Disk Drive Service Manual (EK-0RA60-SV-002 - not available online)

External links