|S,1:|SELECT,"A" - drive A is unit 2.
|S,2:|SELECT,"B" - drive B is unit 2.
== Vortex Disc format ==
Sector numbers are 01h..09h (same as AMSDOS IBM Format, but with a 9th sector).
Disks are Double-Sided, Double Density, 80 Tracks, 9 Sectors, blocks are allocated in 4K units.
Total capacity is 720K (704K available):
* First 9K contain two System Tracks (eg. CP/M Bootstrap)
* Next 4K contain directory (see Note)
* Next 704K are data (allocated in 4K blocks) (aka 4K clusters)
* Last 3K are unused (due to 4K allocation size)
Note: According to the manual, the directory can hold 128 entries under VDOS2.0 (whole 4K used), but only 64 entries under VDOS1.0 (only half of the 4K area used).
== Manual ==