Backward Compatible, High Track Density Floppy System (Read/Write With Dual Width Erase)
Original Publication Date: 1985-Jun-01
Included in the Prior Art Database: 2005-Feb-18
The low track density on an 8-inch floppy diskette is 48 tracks per inch (tpi). The high density is 96 tpi. The 48 tpi system puts down a track 13 mils wide followed by tunnel erase areas 6.5 mils wide. The net result is 13-mil tracks on 21-mil centers (8-mil guard bands on either side of track). See Fig. 1. The dimensions for the 96 tpi system are approximately half of those for the 48 tpi system. This disclosure teaches the use of a narrow, 96 tpi head not only to read and write the high track density disk, but also to read and write the wide track, low density disk. Using the narrow head to read the wide track is straightforward, causes no problems, and needs no further discussion, but updating a 48 tpi disc by writing a narrow track on it in place of the wide track will be explained.