RA80 Disk Drive
From Computer History Wiki
| RA80 | |
| Manufacturer: | DEC |
|---|---|
| Drive Controller(s): | all SDI controllers |
| Capacity: | 121 Mbytes |
| Transfer Rate: | 1.2 Mbytes/sec |
| Average Access Time: | 33 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 per head (total) 546 (usable for data) |
| Sectors per Track: | 31 |
| Bytes per Sector: | 512 |
| Tracks per Inch: | 478 |
| Density: | 6339 (max; inner track) |
| Recording Method: | MFM |
| Start Time: | 15 secs (avg); 40 secs (max) |
| Physical Size: | 26cm x 44cm x 67cm |
| Weight: | 147 lbs (approx) |
| Power Consumption: | 720 watts |
The RA80 Disk Drive is a Standard Disk Interconnect non-removable-media disk drive from DEC. A physically large drive (14-inch platters, in a heavy enclosure 10.5" x 16" x 36"), its capacity was 121 Mbytes.
It had two heads per surface; not rotationally opposed (to halve maximum access time), but two on each arm; there thus 1,092 usable tracks on each surface. It was internally operated by a microprocessor which used 32-bit burst ECC to invisibly repair simple data errors.
It was apparently the SDI version of the R80 Disk Drive. The RA80 can also be connected in a dual-port arrangement, permitting its use by two controllers.
4.3 BSD disktab
a80|RA80|DEC RA80 Winchester:\ :ty=winchester:ns#31:nt#14:nc#559:\ :pa#15884:ba#8192:fa#1024:\ :pb#33440:pc#242606:\ :pg#82080:bg#4096:fg#512:\ :ph#111202:bh#4096:fh#1024:
External links
- ra80 - documentation at Bitsavers
- RA80 Disk Drive User Guide (EK-0RA80-UG-001)
- The RA60, RA80 and RA81 Disk Drives and The Digital Storage Architecture - brochure
