Announced in 1968, this was Mitsubishi Electric's first fixed head magnetic disk unit. The unit achieved high-reliability at an extremely low price by adopting a floating head and simplifying the mechanism. It was used with office computers, minicomputers and other small computers, as well as with automatic testers.
This unit had the following features:
- The floating head followed the disk well, and temperature control to maintain a constant gap between head and disk was unnecessary.
- A head was provided for each track, so access time was short.
- Although the unit was compact and lightweight, it could store 270,000 bits or 540,000 bits, and bit cost was low.
- The system could withstand long-term use due to a hard protective coating of the disk and head, a sealed structure to prevent dust, and anti-corrosion treatment of all parts.
| M-811-1 | M-811-2 | ||
|---|---|---|---|
| Memory capacity | 266,240bit | 532,480bit | |
| Track capacity | 8,320bit | 8,320bit | |
| Recording system | NRZ system or PM system | ||
| Number of data tracks | 32 | 64 | |
| Number of timing tracks | 4 | 4 | |
| Magnetic disks | 8-inch 1side | 8-inch 2 sides | |
| Disk rotation speed | 3,000/3,600rpm | ||
| Rotational delay | Average 10/8.3ms | ||
| Data transfer speed | 416/499Kbit/s | ||
| External dimensions(Diameter×Hight) | 256mm×250mm | ||
| Weight | 15kg | ||
In 1972, Mitsubishi Electric announced further members of this Series: the M-810 with a memory capacity of 100,000 bits, the M-814 with a memory capacity of 1 million bits, and the M-824 with a memory capacity of 2 million bits. The M-810 used a 6-inch magnetic disk and was smaller, with a diameter of 200mm, and the M-814 used an 8-inch magnetic disk and had an increased track capacity of 16,650 bits. The M-824 used a 12-inch magnetic disk, and had an increased track capacity of 33,250 bits.
