Analyser: New and Modified

9 March 2002

An MFM bit stream data type, with automatic MFM recording (not encoding!) detection and adjustable threshold descriptor using the MFM bit stream type. This can detect noise (unformatted) tracks. The scoring for the track reflects if any MFM encoded data is recorded on the track, so a 100% score means no recording - the noise track is completely random. The bit stream type uses a similar algorithm to the bit-by-bit scan to select brute force or smart decoding to speed up an otherwise very time consuming process.

The difference between noise detection through the MFM stream type and noise detected by the density analyser is that the density analyser makes its guesses by using bitcell timings, while the bitstream type actually checks the magnetic recording type. Well... It is actually more than that, since the density scanner is very fast (less than a second for a whole disk) and its results can be used by the descriptors as “hints”. So any format descriptor that has an active hint is checked first to speed up the process. This was slightly broken until today, resulting in testing all formats even if the track was already known to be 100% noise. This was because no format descriptors used this feature before. Naturally, if a format test is not 100% a full analysation occurs.

• Cosmetic changes, like selectors disabled for undumped tracks.
• Fixed format priority algorithm.
• The density “hint” was not used before (it was disregarded), but it is now

With these additions many disks can now be fully decoded. Now time for the data viewer and then save.