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 |
FACOM 472K Grouped Disk Pack Unit |
FACOM 472L Grouped Disk Pack Unit |
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|---|---|---|---|---|---|
| Completion date | August 1969 | March 1970 | September 1972 | ||
| Memory capacity | Track capa -city |
Fixed length | 256byte×10 | 256byte×18 | |
| Variable length | Max.3,625byte | Max.7,294byte | |||
| Disk Pack |
Fixed length | 5.12×106byte | 17.77×106byte | 35.55×106byte | |
| Variable length | 7.25×106byte | 29.18×106byte | 58.36×106byte | ||
| Unit | Number of drives | 1drive | 8drives+ 1spare drive | ||
| Fixed length | 5.12×106byte | 142.18×106byte | 284.36×106byte | ||
| Variable length | 7.25×106byte | 233.41×106byte | 466.81×106byte | ||
| Disk pack |
Number of tracks/side | 203 | 203 | 406 | |
| Number of cylinders/ pack |
203 | 203 | 203 | ||
| Effective number of disks/ number of sides |
6/10 | 11/20 | 11/20 +1 side(Servo) |
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| Disk pack diameter | 356 mm(14inch) | 430 mm(17inch) | |||
| Positioning system | Pulse motor | Linear motor | |||
| Positioning time | Average 75ms (Min. 25ms, Max. 135ms) |
Average 75ms (Min. 30ms, Max. 135ms) |
Average 50ms (Min. 15ms, Max. 80ms) |
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| Rotation speed | 2,400rpm | 2,000rpm | 2,400rpm | ||
| Average rotational delay | 12.5ms | 15ms | 12.5ms | ||
| Data transfer speed | 156Kbyte/s | 260Kbyte/s | 312Kbyte/s | ||
| Main connected systems | *1 |
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*1:·FACOM 462K-1 (Fixed length type): FACOM 230-25/35
·FACOM 462K (Variable length type): FACOM 230-60
