Drive B-A and B-F commands
Date: 2001-10-12 06:04:29

Hi All,

I need some advice about the B-A command as I'm in the middle of
implementing this support to 64HDD and my thinking is to fix the bug(s)
rather than implement them, but am wary of compatibility.

Does anyone know if the B-A bug (which when a block is already allocated, it
allocs the whole track and jumps to the next track to search for a free
block) is only a 1541 trait, or whether it is also in the 1571 and 1581

Also, there is the question of allocation on the directory track. The 1541
as I understand it can return a free block in Track 18, which supposedly it
shouldn't. Do the 1571 and 1581 drives also point to their respective dirs
(eg 18/53 or 40) when the next block is given? 

The 1541 programs I've seen test for T18 being returned and skip the answer
and re-check, but what do the newer drive types. Does anyone know of where
the bug may be relied upon to do some thing useful?

Also, if anyone has any understanding of the behaviour of the FD2000 drive,
regarding the B-A command, this will also be helpful.



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