Rummaging around in my stack of old genealogy research notes, I found a marginal annotation:

size 61496 cyls 7476 head 255 sector 63
precomp 0 landz 16382

…i.e., disk-configuration settings from long ago.

Remember the brief but weird time in which disk capacities had exceeded the limits assumed (and/or imposed) by the IDE interface? For the disk to work, it had to lie to the controller about its geometry: e.g., a four- or six-platter disk pretending to be a 255-platter disk, to keep the cylinder count low enough not to choke IDE.

I can’t remember the last time I had to do that. These days, disks are a thousand times larger, but no foolery is required: plug them in, and they just work.

One thought on “Geometry

  1. Pat Post author

    Capacity 61496 most likely means it was a 60GB disk; these numbers precede the disk manufacturers’ realization that by fudging the value of 1GB they could make their disks seem larger.

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