(01-15-2014, 06:12 PM)LordCrass Wrote: There's 4 different 5.25" formats that I've heard of, although the most common are the 360K double-sided double-density (DSDD) and the 1.2MB double-sided high-density (HD).
The others are 8 and 9 sector single-sided single-density (160K/180K respectively).
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A quick google shows all kinds of other PC formats.. 320KB/400KB/720KB/1440KB, 8 sector double sided, 10 sector, etc..
You have to differentiate between usual and rarer used formats.
1.2MB (80Trk/2S/15Sec/512BpS) and also 1.44MB (80 Trk/2S/18Sec/512BpS) for AT compatibles or better, named "HD", these are the most used formats.
360KB (40Trk/2S/9Sec/512BpS) is also used often for IBM PC XT and Compatibles, named "DD".
All other formats are officially used, but more rare:
720KB (80Trk/2S/9Sec/512BpS), also "DD" but was only used for some PS/2 and early laptops/notebooks.
160KB/180KB (40Trk/1S/8 or 9Sec/512BpS) - "DD" - only used for early PC (XT) and some bootable games.
320KB (40Trk/2S/8 Sec/512BpS) - "DD" - uncommon but also used in the beginning.
(800KB (80Trk/2S/10 Sec/512BpS) - "DD" - only used with additional formatter programs, is supported by higher DOS versions and DRIVER.SYS or DRIVPARM=... )
Note: "HD" was used with 360rpm rotation speed floppy drives, "DD" with 300rpm. Some HD drives can be configured as DD, see http://www.oldskool.org/disk2fdi/525HDMOD.htm ...
There were some DOS TSR programs which extends the BIOS, so all possible combinations can be used, also more than 80 Tracks, but this was not officially supported by Microsoft/IBM.