Hi Peter,

Sure, any help is appreciated. 8-) I got so interested in the silentype I haven't done much with the disk reading stuff for a while.

I've been studying the books Beneath Apple Prodos and Universal File Conversion.

The one thing that had me really stumped was the different sector orders between dos 3.3 and prodos.

[Linked Image]

So dos 3.3 logical sector 1 maps to prodos logical sector 0xE for example.

I came up with this function which seems to work (it's really useful to look at hexdumps).

-- prodos order to dos order
function mappotodo(a) local map={0,14,13,12,11,10,9,8,7,6,5,4,3,2,1,15} return map[a+1] end
-- function has an interesting property: calling it twice results in inverting the function
-- mappotodo(maptptodo(i))  == i
-- example: to hexdump a track in normal dos order
-- for i=0,15 do hexdumpts(0,i) end
-- example: to hexdump the same track in prodos order 
-- for i=0,15 do hexdumpts(0,mappotodo(i)) end