Weird problem writing 'weak flux' pattern
#1
Hi there,

I'm experimenting with reliably writing 'weak flux' areas to disk, as short as 64 MFM bitcells (128us), which will read back randomly. I've settled on the following repeated pattern of 12 flux values: 25us, 0.5us*6, 19us, 0.5us*4

This works well. However for convenience I want to use the same pattern even for much larger weak areas. I have one track which is 44894489 ... a few bytes of header ... 8192 MFM weak bitcells (16ms). Remainder of track is normal null filler.

When I generate above track with my chosen weak pattern, write to disk with Supercard Pro, and then read back, my 44894489 header is missing Sad It seems related to the large number of short (500ns) fluxes I am emitting. If I remove those I get my 44894489 sync back.

I can provide before and after SCP files. Of course these are generated entirely by my own tools, so can't discount I've done something stupid  Wink

 Regards,
 Keir
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Weird problem writing 'weak flux' pattern - by keirf - 01-07-2016, 05:53 AM



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