WDC1772 Data Access Framework Complete

20 November 2004

Disk access framework implemented.

To enhance performance, only events that can happen within the specific context (i.e. non generic) are processed. This divides access into the following different execution paths:

1. Read line is not connected to the FDC, which happens when no drive is selected. While the FDC halts on spin-up sequence early if this happens (since with drives deselected other lines are disconnected as well, like the index pulse that is used as a retry count by the FDC) it is possible to start and deselect a drive while in progress.
2. Read line is fed with random data, like on unformatted tracks, etc.
3. Read line is fed with real data from normal density tracks, that is, density does not change within a track.
4. Read line is fed with real data from variable density tracks, that is, density changes within a track.

Now (1) works.