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Keir · 27 February 2018, 12:10

I debugged this for FlashFloppy and the bug is in Ziriax track loader.

For efficient sector scanning it skips 300*2 MFM bytes at the track gap. However this assumes the track is at least (544*11 + 300)*2*8 = 100544 bitcells long.

However a DD track is 100000 bitcells +/- perhaps 2%. Usually drives run a bit slow and you end up with a long enough track, but this is certainly not guaranteed.

Works on HxC because it generates long-ish tracks for ADF (101372 bitcells).

I fixed the track loader to skip 0x11A (=141*2) MFM bytes instead (conservatively assumes track is >= 98000 bitcells) and that works fine for me on FlashFloppy.

27 February 2018, 12:10	#61
Keir Registered User Join Date: May 2011 Location: Cambridge Posts: 682	I debugged this for FlashFloppy and the bug is in Ziriax track loader. For efficient sector scanning it skips 3002 MFM bytes at the track gap. However this assumes the track is at least (54411 + 300)28 = 100544 bitcells long. However a DD track is 100000 bitcells +/- perhaps 2%. Usually drives run a bit slow and you end up with a long enough track, but this is certainly not guaranteed. Works on HxC because it generates long-ish tracks for ADF (101372 bitcells). I fixed the track loader to skip 0x11A (=1412) MFM bytes instead (conservatively assumes track is >= 98000 bitcells) and that works fine for me on FlashFloppy. Last edited by Keir; 27 February 2018 at 12:22.*