RA82 disk drive
From Computer History Wiki
| RA82 | |
| Manufacturer: | DEC |
|---|---|
| Drive Controller(s): | all SDI controllers |
| Capacity: | 622 Mbytes (formatted) 855 Mbytes (un-formatted) |
| Transfer Rate: | 2.4 Mbytes/sec |
| Average Access Time: | 32.3 msec |
| Revolutions per Minute: | 3600 |
| 1/2 Revolution Time: | 8.3 msec |
| One Track Seek Time: | 6 msec |
| Average Seek Time: | 24 msec |
| Maximum Seek Time: | 38 msec |
| Total Surfaces: | 7 data, 1 data/servo (shared) |
| Number of Heads: | 15 data, 1 servo (read-only) |
| Tracks per Surface: | 1423 (usable, per head) 1435 (total, per head) |
| Sectors per Track: | 57 (usable) 58 (total) |
| Bytes per Sector: | 512 |
| Tracks per Inch: | 1063 |
| Density: | 12,545 |
| Recording Method: | MFM |
| Start Time: | 50 secs (max) |
| Stop Time: | 20 secs (max) |
| Physical Size: | 26cm x 44cm x 67cm |
| Weight: | 172 lbs |
| Power Consumption: | 560 watts (idle) |
The RA82 disk drive is a Standard Disk Interconnect non-removable-media disk drive from DEC. It is member of the Digital Storage Architecture. A physically large drive (14-inch platters, in a heavy enclosure 10.5" x 16" x 36"), its capacity was 622 Mbytes.
It had two heads per surface; not rotationally opposed (to halve maximum access time), but two on each arm; there thus 2,846 usable tracks on each data surface. It was internally operated by a pair of microprocessors, which used 32-bit burst ECC to invisibly repair simple data errors. An RS232 port was provided for diagnostic purposes.
The RA82 can also be connected in a dual-port arrangement, permitting its use by two controllers.
External links
- ra82 - documentation at Bitsavers
- RA Family Of Winchester Disk Drives - brochure
- RA82 Disk Drive User Guide (EK-0RA82-UG-001)
