SVMAP - Save allocation Map to disk.

Syntax:

CALL 4017H

Input:

The corresponding drive must be switched on.

The current allocation map is in the DOS work area іп MAPAREA.

Exit:

The sector map was written to sector 15 of track 0 on the floppy disk in the selected drive.

The drive remains powered on.

Registers used:

AF, BC. DE, HL

Error handling:

In the event of an error, this routine automatically branches to the ERROR routine. Custom error handling is not possible.

The sectors allocation map is transferred from the corresponding buffer of the Memory resident workspaces (MAPAREA) to the data buffer and written from there to sector 15 of track 0 on the diskette.

Note that you must turn the drive on and off by yourself.

Before saving, check that the floppy disk is not write-protected,

Example:

...
DI                  ; disable interrupts
LD A,10H            ; select Drive 1
LD (IY+11),A
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!
CALL 4017H          ; write back allocation map
CALL 400BH          ; turn off drive
EI                  ; enable interrupts again
...

The sector allocation overview is written back from the Memory resident workspaces (MAPAREA) to the diskette in drive 1 (track 0, sector 15).

Internally called routines: WRITE