RM80 Disk Drive
| RM80 | |
| Manufacturer: | DEC |
|---|---|
| Year Introduced: | October, 1980 |
| Drive Controller(s): | RH11, RH70, RH10, RH20, RH780, RH750 |
| Capacity: | 124 Mbytes |
| Transfer Rate: | 1.2 Mbytes/sec |
| Average Access Time: | 33.3 msec |
| Revolutions per Minute: | 3600 |
| 1/2 Revolution Time: | 8.3 msec |
| One Track Seek Time: | 6 msec |
| Average Seek Time: | 25 msec |
| Maximum Seek Time: | 50 msec |
| Total Surfaces: | 7 data, 1 servo |
| Number of Heads: | 14 data, 1 servo (read-only) |
| Tracks per Surface: | 561 (18-bit word mode) 559 (16-bit word mode) |
| Sectors per Track: | 30 (18-bit word mode) 31 (useable; 16-bit word mode) |
| Words per Sector: | 256 (16-bit word mode) |
| Tracks per Inch: | 478 |
| Density: | 6339 (max; inner track) |
| Recording Method: | MFM |
| Start Time: | 20 secs (avg); 40 secs (max) |
| Stop Time: | 9 secs (avg); 13 secs (max) |
| Physical Size: | 26cm x 44cm x 67cm |
| Weight: | 135 lbs (approx) |
| Power Consumption: | 575 watts |
The RM80 Disk Drive was a MASSBUS non-removable-media disk from DEC; it held 124 MB. It was apparently the MASSBUS version of the R80 Disk Drive; it could support either 16- or 18-bit words. It was internally operated by a microprocessor which used 32-bit burst ECC to invisibly repair simple data errors.
It had two heads per surface; not rotationally opposed (to halve maximum access time), but two on each arm; there were thus 1,122 usable tracks on each data surface (in 18-bit word mode; 4 tracks were reserved for maintenance purposes in 16-bit mode). 1 sector per track was reserved for bad block replacement in 16-bit word mode, out of 32 total.
The RM80 can also be connected in a dual-port arrangement, permitting its use by two controllers.
Further reading
- RM80 Disk Drive Technical Description Manual (EP-0RM80-TD-001) - not available online, but in microfiche
- RM80 Disk Drive Service Manual (EP-0RM80-SV-001) - not available online, but in microfiche
