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Manufacturer: Digital Equipment Corporation
Drive Controller(s): all DSSI Controllers
Capacity: 852 Mbytes (formatted)
Transfer Rate: 4.0 Mbytes/sec
Average Access Time: 15.1 msec
Average Seek Time: 9.5 msec
Start Time: < 30 sec
Stop Time: < 15 sec
Physical Size: 3.5" half height

The RF35 is a DSSI hard drive produced by Digital Equipment Corporation from about 1991. This is called an 'Integrated Storage Element' (ISE), which combines the Head-disk assemblies (HDA) and a controller with MSCP server. The MSCP server allows the disk to queue I/O requests from multiple hosts at a time. One of the use cases for this feature is to provide storage to a VAXcluster made of small systems like the MicroVAX.

The drive uses a 50-pin DSSI interface and a 5-pin Molex power connector, providing access to 852 MB of storage. There are 7 platters, each with 2 heads, for a total of 14 data surfaces and ~60MB per surface. The disk geometry is 14 tracks, 2,086 cylinders, 58 sectors per track (including 1 replacement sector).

The disk controller contains a MC680x0 microprocessor, RAM, and NVRAM. A number of diagnostic and utility programs are available to the controller. At startup, there is a POST test and diagnostics continue executing periodically while the disk runs. In addition to error codes visible via the diagnostic programs, the disk has an amber-colored Fault LED.

The RF31T is a lower-capacity version of the RF35, but with an improved seek rate.

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