RDMAP - Load allocation Map

Syntax:

CALL 4011H

Input:

The corresponding drive must be switched on.

Exit:

The sector allocation map is located in the 80-byte buffer at the end of the Memory resident workspaces (MAPAREA).

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 loaded from sector 15 of track 0 from the diskette into the main memory and transferred to the MAPAREA at the end of the Memory resident workspaces.

Note that you are responsible for turning the drive on and off yourself.

Example:

...
DI              ; disable interrupts
LD A,10H        ; select Drive 1
LD (IY+11),A
CALL 4008H      ; and turn on
LD BC,50
CALL 4038H      ; 50 ms delay
CALL 4011H      ; load allocation map
CALL 400BH      ; turn off the drive
LD L,(IY+52)    ; start address of allocation map ..
LD H,(IY+53)    ; .. into HL
EI              ; enable interrupts again
...

The sector occupancy overview is loaded from the floppy disk in Drive 1. The start address of the MAPAREA is then made available in the register pair HL.

Internally called routines: READ