The FACOM 472K was Fujitsu's first grouped disk pack unit, which provided 9 disk drives with a controller, and was completed in March 1970.
Fujitsu had the FACOM 462K which used IBM compatible disk packs (comprised of six 14-inch disks), but in order to achieve higher capacity and higher speed, Fujitsu developed their first grouped disk pack unit which enabled use of up to a maximum of 9 disk drives (8 drives for normal use, and 1 drive as a spare) for Fujitsu unique disk packs (each comprised of eleven 17-inch disks). There were two recording formats, fixed length and variable length. The former type was connected to the SFC (Sector File Channel) of the FACOM 230-35 mid-size general-purpose computer, and the latter was connected to the SLC (Selector Channel) of large general-purpose computers such as the FACOM 230-45S or higher models. The FACOM 472K had the following features:
- 1) A high-capacity memory of 29Mbytes per pack was achieved by using a disk pack comprised of eleven 17-inch disks.
- 2) As a subsystem, it was possible to connect a maximum of 8 normal use drives and 1 spare drive, thereby achieving a maximum memory capacity of 233Mbytes.
- 3) High-speed data transfer at 260Kbyte/s was achieved.
- 4) One or two drives could be housed in a single cabinet. Drives were the drawer type and could be slid forward and back. Disk packs could be removed, mounted, maintained and inspected independently of other drives.
- 5) It was possible to easily and accurately configure combinations of media and access equipment numbers by reinserting equipment number plugs (from 0 to 7) into the desired drive.
In September 1972 Fujitsu completed the FACOM 472L Grouped Disk Pack Unit which increased the memory capacity of a single pack to 58Mbyte by doubling the number of tracks, and reduced the average positioning time to 50ms by employing a linear motor as the positioner.
|(Reference) FACOM 462K/462K-1
Disk Pack Unit
Grouped Disk Pack Unit
Grouped Disk Pack Unit
|Completion date||August 1969||March 1970||September 1972|
|Memory capacity||Track capa
|Unit||Number of drives||1drive||8drives+ 1spare drive|
|Number of tracks/side||203||203||406|
|Number of cylinders/
number of disks/
number of sides
|Disk pack diameter||356 mm(14inch)||430 mm(17inch)|
|Positioning system||Pulse motor||Linear motor|
|Positioning time||Average 75ms
|Average rotational delay||12.5ms||15ms||12.5ms|
|Data transfer speed||156Kbyte/s||260Kbyte/s||312Kbyte/s|
|Main connected systems||*1|