Tuesday, October 20, 2015

Dellivery and inspection of Diablo Model 31 disk drive

Another extremely busy day with the day job. At the end of the day, my ebay purchase of a disk drive was delivered and that was the only thing I could spend a brief period of time looking over.


The Diablo disk drive arrived today - potentially a twin for the one that came with my 1130 system. That original Diablo drive had suffered a head crash but appeared to be otherwise intact. The new one has nice clean heads and is in fairly good shape.

Drive opened and card cages raised for inspection
There is a touch of a mildew smell and some signs of aluminum corrosion on the outer handle from exposure to humidity. I bought it from a seller in Florida which made this a likelihood. It doesn't appear to have affected anything important, although the other brushed aluminum is a bit impacted.

There is a metal restraint that is part of the cartridge receiver mechanism which has a very light layer of oxidation on it, the only place I see any inside the machine. Still, this warrants a strip down, good cleaning and repainting of the restraint and any other surfaces that may be impacted.

Black restraint (upside down U shaped bar) with oxidation visible on surface
The Diablo model 31 can be ordered with a wide range of options, some of which will eliminate the chance that this drive could be media and data compatible with my existing 2315 cartridges and stored software. The drive can run with four linear densities, but for compatibility with the 1130 system this has to be the 'standard' 1100 bits per inch. If so, at the minimum I can swap the heads into the other drive and go.

Another set of options controls which sectoring scheme is used on the cartridges. The 1130 system uses 8 sector markers around the edge, but the Diablo drive could have various alternatives up to 32 sectors. This affects the logic in various ways, such as matching a read/write request to a target sector, and therefore an incompatible option might require me to hack the circuitry.

Unfortunately, the disk drive vendors of the day didn't bother marking the options anywhere on the drives, so I can't just look for a spot that lists which variant I have. I can probably dig through the logic cards and find some indication of the choice made.

Label on drive that came with the 1130 system

Label from newly acquired drive

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