justinhaynes@my-deja.com writes: >1) What are the specifications for the floppy disk format used with the >apple IIGS on these old 3.5" drives 800KB, 8-12 512 byte sectors per track (16 tracks per zone), 2 sides. >2) are there any real physical differences in the way these disk drives >deal with disks compared to drives you would find elsewhere, and where >can I read about these differences GCR vs MFM recording. Read Inside Apple DOS or Inside Apple ProDOS for info on GCR (as used on Apple 140KB 35 track 5.25" disks), any decent book on disk drives for info on MFM. >3) Does anyone know where I can find these kinds of standards >generally? I tried IEEE, but couldn't find anything. Data sheets for the early FDC chips (1790 etc from WD I think) had much info on FM & MFM formats. Here is my list of floppy disk formats: disk speed data rate trk sector trk/hd size rpm s/rev kb/s scheme kb cnt*sz count KB -------------------------------------------------------------------------------- 8" 360 0.167 500 FM 41.67 26*128 77/1 260 SSSD (8) 8" 360 0.167 500 FM 41.67 26*128 77/2 520 DSSD (8) 8" 360 0.167 500 MFM 83.33 26*256 77/1 520 SSDD (9) 8" 360 0.167 500 MFM 83.33 26*256 77/2 1040 DSDD (9) 5.25" 300 0.200 250 FM 25.00 8*256 40/1 80 SSSD 5.25" 300 0.200 250 FM 25.00 8*256 40/2 160 DSSD 5.25" 300 0.200 245 GCR 49.00 16*256 35/1 140 SSDD (1) 5.25" 300 0.200 250 MFM 50.00 8*512 40/1 160 SSDD (3) 5.25" 300 0.200 250 MFM 50.00 9*512 40/1 180 SSDD (3) 5.25" 300 0.200 250 MFM 50.00 8*512 40/2 320 DSDD (3) 5.25" 300 0.200 250 MFM 50.00 9*512 40/2 360 DSDD (3) 5.25" 300 0.200 250 MFM 50.00 9*512 80/2 720 DSDD 5.25" 360 0.167 300 MFM 50.00 9*512 40/2 360 DSDD (4) 5.25" 360 0.167 300 MFM 50.00 9*512 80/2 720 DSDD 5.25" 360 0.167 500 MFM 83.33 15*512 80/2 1200 DSHD (4) 3.5" 300 0.200 250 MFM 50.00 9*512 80/2 720 DSDD (5) 3.5" 300 0.200 250 MFM 50.00 5*1024 80/2 800 DSDD (2) 3.5" var var var GCR var var*512 80/2 800 DSDD (7) 3.5" 300 0.200 250? MFM? 50.00? 11*512 80/2 880 DSDD (B) 3.5" 300 0.200 500 MFM 100.00 18*512 80/2 1440 DSHD (6) 3.5" var var var GCR var var*512 80/2 1600 DSHD (A) 3.5" 300 0.200 500? MFM? 100.00? 22*512 80/2 1760 DSHD (C) 3.5" 300 0.200 1000 MFM 200.00 36*512 80/2 2880 DSED (1) Apple ][ (2) Applix (3) IBM PC (4) IBM PC/AT (5) IBM PS/2 25,30 (6) IBM PS/2 > 30 (7) Macintosh & Apple // (8) IBM 3740 (9) IBM System 34 (A) AE 1.6MB drive on Apple // (B) Amiga DD (C) Amiga HD IBM System 34 format 256 byte sectors 12 * 00 3 * F5 1 * FE 1 * Track# 1 * Side# 1 * Sector# 1 * SecLen 2 * CRC 22 * 4E 12 * 00 3 * F5 1 * FB 256 * data 2 * CRC 54 * 4E ------ 372 bytes = 2976 bits -- David Wilson School of IT & CS, Uni of Wollongong, Australia