Mike Douglas f3af74e444 AltairZ80: Fix head stepping to only occur on 1 to 0 transitions ...

The source file to be updated provides emulation of the North Star DD
floppy disk controller. The proposed change steps the head only when the
step bit in the order byte transitions from 1 to 0. This is the way the
actual hardware functions. Previously, the emulation would step any time
an order was issued and the step bit was 1. This behavior caused some
original software (e.g., Lifeboat CP/M 2.2) to end up on an incorrect
track.

2015-08-08 21:27:09 -05:00

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