Section VI
                               Useful ROM Subroutines (2.3)

Address     Description

C000-C002   DOS Version Number ("2.3")
C003        Turns on LED 0 or LED 1, based on DRVNUM ($0054)
C00F        Kills any error status on the LEDs
C018        Turns off LED 0 or LED 1, based on@DRVNUM ($0054)
C036        Invokes an error flash on LED 0 or LED 1, based on DRVNUM
E83F        Start of RESET code (jump here to reset drive)
F46C        Search for header in $4C28-4C2C. Return with .z=1 if
              not found; .z=0 if found.
F4A6        Search up to 30mS for a SYNC (.c=0 if found)
F68A        Wait loop. Waits for .X milliseconds.

            Example:       LDA #100      ;set up a 100 mS delay
                           JSR $F68A     ;

F693        Move the head of drive number in $D0 to track number .A
              Also, sets read density after head is moved.

            Example:       LDA #0        ;drive 0
                           STA $B0       :store drive 0
                           LDA #20       ;target = track 20
                           JSR $F693     :move there

F700        Move the head of drive number in $B0 to track 0.
              Also, sets read density after head is moved.

            Example:       LDA #0        :drive 0
                           STA $B0       :store drive 0
                           JSR $F700     ;move to track 0

F754        Turn on Drive 0, Turn off Drive 1
F759        Turn off both drives
F767        Turn on Drive 1, Turn off Drive 0

FE11        Set Port B in the IEEE mode (See section II E)
FE1A        Set Port 8 in the Read mode (See section II E)
FE25        Set Port B in the Status Mode (See section II E)