This was a hard disk unit for small computers, announced in 1978 by Mitsubishi Electric. It corresponded to the unit (Model 62GV) incorporated by IBM Corporation into its System 32 and 34, and among equivalent products, it enabled expansion of memory capacity up to 80.8MB, the highest among Japanese manufacturers. Furthermore, a 2.43MB fixed head could be added as an option. Thus a single unit could be simultaneously equipped with high-capacity files as well as high-speed memory. Its features included compactness and maintenance-free performance, and it was used as an external memory device in a wide-range of systems, such as office computers and minicomputers.
This unit had the following features:
- There were 4 models, ranging from a minimum capacity of 13.4MB to a maximum capacity of 80.8MB, and memory capacity could be selected to suit the application.
- A fixed head (with a capacity of 0.81MB or 2.43MB) could be mounted in addition to the movable head.
- The unit maintained compactness, even with a built-in power supply, and could be mounted in a standard 19-inch rack.
- A completely sealed structure eliminated contamination of the disk surface with dust and made periodic maintenance unnecessary.
| Unit memory capacity | 13.4MB(model 10),26.9MB(model 20), 53.8MB(model 30),80.8MB(model 40) Fixed head section:0.81MB or 2.43MB |
|---|---|
| Track capacity | 20,160byte |
| Recording system | MFM |
| Bit density | 6,060bit/inch |
| Track density | Movable head 286track/inch Fixed head 33.3track/inch |
| Data transfer speed | 996Kbyte/s |
| Positioning time | Min. 10ms,Max. 75ms,Average 38ms |
| Rotational delay | Average 10.12ms |
| Rotation speed | 2,964rpm |
| Memory media | Disk diameter 14-inch Number of disks 1-4 |
| Number of heads | Movable heads 2-12 Fixed heads 0-40 servo heads 1 |
| External dimensions | 451mm×178mm×610mm |
| Weight | 30kg |
