STPIN - Advance read/write head n tracks

Syntax:

CALL 403BH
Input:

  • The drive must be powered on.

  • B = number of tracks

Exit:

  • The read/write head was set in front of the corresponding number of tracks.

  • DTRCK (IY+20) contains the new current track number.

Registers used:

AF, BC

Error handling:

none

The read/write head is advanced by the number of tracks contained in B, but up to track 39 at most.

Example:

...
DI                  ; disable interrupts
LD (IY+11),10H      ; select Drive 1
CALL 4008H          ; and turn on
LD BC,50            ; 50 ms delay
CALL 4038H
LD B,10             ; put head in front of tracks
CALL 403BH
CALL 400BH          ; turn off drive
EI                  ; enable interrupts again
...