This was a high-capacity removable magnetic disk unit announced by Mitsubishi Electric in 1973. It was a equivalent of the IBM3330 magnetic disk unit, and had a memory capacity of 100MB per spindle and a high-speed positioning mechanism which required 30ms on average. This unit was used for data files for mid-size to large computers such as the MELCOM 7000 Series and COSMO Series.
This unit had the following features:
- It exploited high-density magnetic recording technology to achieve a track density of 192track/inch and a bit density of 4040bit/inch, and used the MFM (Modified Frequency Modulation) system to achieve the high capacity.
- Positioning at higher speed and precision was enabled by using a track-servo system which employed a linear motor in place of the conventional hydraulic positioning system.
- A rotational position detection mechanism and high-reliability automatic maintenance functions reduced the burden on the disk controller and improved availability. Diagnostic programs enabled self-diagnosis.
- By using Mitsubishi's unique self-pressing magnetic head technology, the system simplified and lightened the head pressing/holding mechanism, and realized faster access times.
| Unit memory capacity | 100MB |
|---|---|
| Track capacity | 13,440byte |
| Positioning time | Average 30ms |
| Rotation speed | 3,600rpm |
| Bit density | 4,040bit/inch(159bit/mm) |
| Track density | 192track/inch(7.5Track/mm) |
| Data transfer speed | 806Kbyte/s |
| Recording system | MFM |
| Memory media | IBM3336 or the equivalent Disk diameter : 14inch(356mm) Number of disks : 10 + 2(protected) Data recording sides : 19 servo sides: 1 Number of cylinders : 404 + 7(spare) Weight : 9kg |
| External dimensions(Width x Height x Depth) | 640mm×1,100mm×950mm |
| Weight | 250kg |
The M2837, its enhanced model, was announced in 1975. It achieved a memory capacity of 200MB by doubling the track density to 370track/inch, and setting the number of cylinders to 808 + 7 (spare).
The M2838F, further enhanced model, was announced in 1979. It achieved a memory capacity of 300MB by increasing the bit density 1.5 times to 6,060bit/inch, and adopting a track capacity of 20,160 bytes.
