1802



1802           70A            DRVBYT
     The maximum number of disk drives in your system, the DOS 2.0
     default value is two. The least four bits are used to record which
     drives are available, so if you have drives one, three and four,
     this location would read:

     00001101 or 13 in decimal.

     Each drive has a separate buffer of 128 bytes reserved for it in
     RAM. If you have more or less than the default (two), then POKE
     1802 with the appropriate number:

     1 drive  =  1 BIT 0                Binary 00000001
     2 drives =  3 BITS 0 & 1                  00000011
     3 drives =  7 BITS 0, 1 & 2               00000111
     4 drives = 15 BITS 0, 1, 2 & 3            00001111

     This assumes you have them numbered sequentially. If not,
     POKE the appropriate decimal translation for the correct binary
     code: each drive is specified by one of the least four bits from one
     in BIT 0 to four in BIT 3. If you PEEK (1802) and get back three,
     for example, it means drives one and two are allocated, not three
     drives.

     You can save your modification to a new disk by calling up DOS
     and choosing menu selection "H." This new DOS will then boot
     up with the number of drives and buffers you have allocated. A
     one-drive system can save 128 bytes this way (256 if one less data
     buffer is chosen). See the DOS Manual, page G.87.

1900           76C            BSIO
     Entry point to FMS disk sector I/O routines.

1906           772            BSIOR
     Entry point to the FMS disk handler (?).

1913           779            ....
     Write verify flag for disk I/O operations. POKE with 80 ($50) to
     turn off the verify function, 87 ($57) to turn it back on. Disk write
     without verify is faster, but you may get errors in your data. I
     have had very few errors generated by turning off the verify
     function, but even one error in critical material can destroy a
     whole program. Be careful about using this location. You can
     save DOS (as above with menu selection "H") without write verify
     as your new default by writing DOS to a new disk. See the DOS
     Manual, page F.85. K-DOS's write-verify flag is located at 1907
     ($773).

1995           7CB            DFMSDH
     Entry point to a 21-byte FMS device (disk) handler. The address
     of this handler is placed in HATABS (locations 794 to 831; $31A