Weird problem writing 'weak flux' pattern
#14
(02-07-2016, 09:04 AM)admin Wrote: The rotation of the data will work for all cases *except* disks where they locate a header, step the head, and expect the data to be exactly what is needed (track skew protection).  I ran into quite a few cases of this with the Supercard Ami for the Amiga (which handled this), and this is why I have a SPLICE mode for the SuperCard Pro.

Typically, you don't need to introduce any type of randomness for weakbit data - just write the data you get. If the flux is invalid, it will remain invalid.  Most images for UAE are single revolution, because almost all commercially produced disks were index aligned.

Yes I've seen several such protections on Amiga. None have straddled the index so they all work fine with my simple-minded method Smile

I'm not sure I'm convinced about the "write back what you read" argument. Some floppy read circuits seem to have a tendency to pull bits into the timing window, so what you read is not what was originally written, and if you were to write it back I'm not sure it would work well, at least for short weak regions. It's a moot point for emulation anyway: if you only have one revolution then something has to inject randomness or you generate the same bitstream on every revolution.
Reply


Messages In This Thread
RE: Weird problem writing 'weak flux' pattern - by keirf - 02-07-2016, 09:34 AM



Users browsing this thread: 1 Guest(s)