List of the EXDOS floppy driver capatibilities:
-can handle four drives (A,B,C,D)
-drive can be a 40 or 80 tracks, single or double sided, any combination of these
-drive types can be mixed in any combination
-40 tracks disks can be used in 80 tracks drive with double stepping
-disk compatibility checked, double stepping automaticaly switch on or off
-at non compatibility situation (80 track disk in 40 track drive or a double sided disk in single sided drive) error reported
-handle 8,9,10,11 sectors/track disks
-plus tracks don't problem (I have a 90 tracks drives
), most commonly used disk format 84x2x10=840K
-don't use Drive Ready signal, then no problem with modern drives
-at default don't use Disck Change signal, then also no problem with modern drives
-works reliable at different speed machines (from 4 to 10Mhz tested yet)
-exist a Turbo EXDOS hack, where WD overclocked to 10Mhz then 13 sectors/track can be stored with normal DD disks and drives, it is can be work both WD1770 and 1772
-more Turbo
, 13.333Mhz for 1.2M drives (300rpm mode) with HD disks, and 16Mhz for 1.44M drives with HD disk. With 1.44 drive can be up to 22 sectors/disk. Exist a different configuration where 1.2M drives run at 360rpm then 9.6Mhz used for handle DD disks, and 16MHz for HD.
At file system level (these also valid for fixed disk volumes):
-probably all options of FAT filesystem supported, for example FAT copies can be from 1 to 7
-FAT copies really used as backups, if any FAT sector unreadable, then automaticaly try to use same sector from the next copy
-instead the hw Disk Change use a sw disk change checking, for this store 32 bit disk serial number in the boot sector. At todays the updated formating programs generate a combined boot sector which are have same serial number for EP and PC.
-can handle early MS-DOS 1.x disk which not have a BPB, and Apricot disks which have a non standard BPB
-for UNDEL store the first character of filename in directory entry. Allocation information not deleted from the last FAT sector, this situation marked in boot sector with Dirty Disk Flag.
Another:
EXDOS card built with WD1770 or WD1772, at 1770 the step rate 0 are the fastest, 6ms. With 1772 the step rate 3 will be faster, 3ms. About 99% of the drives in the world can be used with 3ms, then faster and quiet. (The fastest with 1772 the step rate 2 which are 2ms.) EXDOS have a variable where can selecet the step rate.
Most of them will also needed from SymbOS
I think need a Setup option or Configuration windows or something
for select step rates and enable/select turbo modes.
