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IBM Options and Adapters - IBM PC 20MB Fixed Disk Drive Adapter

From RetroTechCollection

The IBM Personal Computer 20MB Fixed Disk Drive Adapter section of IBM's Options and Adapters technical reference, dated 17 March 1986, documents the later switch-selectable variant of the IBM Fixed Disk Adapter.

What it contains

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  • Types of drives — IBM's own table of the four supported geometries: type 1 at 306 cylinders and 4 heads with write precompensation from cylinder 0 and a landing zone of 306; type 2 at 615 cylinders and 4 heads, precompensation from 300, landing zone 615; type 13 at 306 cylinders and 8 heads, precompensation from 128, landing zone 336; and type 16 at 612 cylinders and 4 heads, precompensation from 0, landing zone 663.
  • Switch settings — switches 1 and 2 select the type for drive 0, switches 3 and 4 for drive 1.
  • Programming — status register, sense bytes, data register and programming summary.
  • Connectors and logic diagrams — connector specifications and the full schematic.
  • BIOS listing — the complete assembler source of the adapter ROM, including the 1701 message.

Download it here: IBM Options and Adapters - IBM PC 20MB Fixed Disk Drive Adapter.pdf

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