On Mon, 3 Sep 2001, Ruud Baltissen wrote:
|Hallo allemaal,
|
|I'm busy in developing a new Kernal for the 1541/IDE combination. And as
|I already thought, that's no peanuts. So now and then I could use some
|help.
Okay.
|I am more a techie and the kind of help I need now is more mathematical
|orientated ie. number crunching.
|
|1) What I need is a conversion from "Track/Head/Sector" to a lineair
|number. And vica versa of course.
|
|Information you need:
|HDTRACKL = Low byte number of tracks on harddisk
|HDTRACKH = High byte number of tracks on harddisk
Are you implying there is a maximum of $ffff tracks on a hard drive?
|HDHEADS = number of heads
|HDSECT = number of sectors on a track.
Do you need an entire 8 bit byte to keep track of HDHEADS? Or can it
be just 1 bit wide? How many hard drive heads are there with an IDE
drive? What legal values are permissible for HDSECT?
|Counting starts with track 0, head 0, sector 1. The next track to be
|read is track 0, head 1.
|
|2) This lineair number is needed to calculate the place of the bit
|representing the bit in the BAM-table.
|
|Information you need:
|BAMBYTES = needed bytes to represent the # of free sectors and the state
| of each sector. The bytes form together a "unit".
I suggest reading in the byte that specifies Disk type to see how big
the BAM should be.
|BAMUNITS = number of units in a BAM-sector, only whole units are used
|
|The structure of a UNIT is conform the one of a 1541.
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