RS11 disk drive

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Manufacturer: Digital Equipment Corporation
Drive Controller(s): RF11 (UNIBUS)
Capacity: 524 KB
Transfer Rate: 125 KB/sec
16 μsec/word (60 Hz)
19.2 μsec/word (50 Hz)
Minimum Access Time: 258 16 μsec
Average Access Time: 16.9 msec (60 Hz AC power)
20.3 msec (50 Hz)
Maximum Access Time: 33.6 msec (60 Hz)
40.3 msec (50 Hz)
Revolutions per Minute: 1800 (60 Hz)
Media: single fixed nickel-cobalt plated surface
Total Surfaces: 1
Tracks per Surface: 128
Density: 1900 bits/inch
Recording Method: NRZI
Power Consumption: 6.5A (operating)
14A (starting)

The RS-11 is a fixed-platter fixed-head disk drive which could store up to 524KB of data, addressable on 16 bit word boundaries (most other DEC disk drives of this era used 512 byte blocks). The drive used 128 fixed read/write heads, and recorded data on a single nickel-cobalt plated surface.

It provided one parity bit per word; data words are stored in a 22-bit format, with guard bits (2 at the start, and 2 at the end) and a sync bit. A spare set of 3 timing tracks, recorded in phase with the primaries, provided redundancy for the 3 primaries..

It was packaged for rack mounting in a standard 19 inch rack, such as an H960. Its controller was the RF11 disk controller (also rack mounted).