WRITE - Write sector to disk

Syntax:

CALL 4032H
Input:

  • The drive must be powered on.

  • The sector to be written must be in the data buffer.

  • The address of the sector to be written must be in the SCTR and TRCK fields of the DOS vectors.

Exit:

The sector in the data buffer was transferred to the diskette.

Registers used:

AF, BC, DE, HL, BC’, DE’, HL’

Error handling:

  • A = 0 Ok, sector written

  • A = 9 An address mark was not found

  • A =17 BREAK key pressed

The sensitive data in the data buffer are transferred to the addressed sector of the diskette. The checksum is determined and placed at the end of the sector.

The sector is transferred including the data mark (10 bytes) in front of the data buffer and the checksum, means a total of 140 bytes are written to the diskette.

Example:

...
DI                  ; disable interrupts
LD (IY+11),10H      ; select Drive 1
CALL 4008H          ; and turn on
LD BC,50            ; 50 ms delay
CALL 4038H
IN A,(13H)          ; check write protection
OR A
LD A,4
JP M,400EH          ; read only, to the ERROR routine
LD (IY+17),10       ; set Sector Number in SCTR
LD (IY+18),5        ; set Track Number in TRCK
CALL 4023H          ; write sector to disk
OR A                ; error occurred?
JP NZ,400EH         ; yes, to the ERROR routine
CALL 400BH          ; turn off drive
EI                  ; enable interrupts again
...

The data from the data buffer is written to track 5, sector 10 of the floppy disk in drive 1.

Internally called routines: IDAM