UNIVAC FASTRAND

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FASTRAND was a magnetic drum mass storage system built by Sperry Rand Corporation for their UNIVAC 1100 series and 490/494 series computers.

A voice coil actuator moved a bar containing multiple single track recording heads, so these drums operated much like moving head disk drives with multiple disks. The heads "flew" on self acting hydrodynamic air bearings. The drums had a plated magnetic recording film.

The Fastrands were very heavy (5,000 pounds) and large, approximately 6' long. They required special rigging and mounts to install.

FASTRAND II

There were three models of FASTRAND drives:

FASTRAND I had a single drum rotating at 15 times per second (880 RPM). The large mass of the rotating drum caused gyroscopic activity, making the unit spin slowly on the computer room floor as the Earth rotated.
FASTRAND II (the majority of units produced) had two counter-rotating drums to eliminate the gyroscopic instability. One actuator bar with heads was located between the drums.
FASTRAND III increased the recording density by 50%.

[edit] Specifications (FASTRAND II)

Storage capacity: 22,020,096 36-bit words = 132,120,576 6-bit FIELDATA characters = 99 megabytes (8-bit bytes) per device
Drum rotation rate: 15 per second (880 RPM)
Heads: 64
Sector size: 28 36-bit words
Track size: 64 sectors (1,792 36-bit words)
Track density: 105 tracks per inch
Average latency (seek plus rotational): 92 milliseconds
Data transfer rate: 26,283 36-bit words per second = 118 kilobytes per second (8-bit bytes)
Recording density, one-dimensional: 1,000 bits per inch (along one track)
Recording density, two-dimensional: 105,000 bits per square inch of drum surface
Max FASTRAND devices (drum units) per controller: 8
Controller price: $41,680 (1968 dollars)
FASTRAND device price: $134,400 (1968 dollars)
Weight per FASTRAND device: 4,500 pounds
Weight per kilobyte: 6 ounces