LOAD - Loading a program or memory area

Syntax:

CALL 4041H
Input:

  • Filename in FNAM (IY+1)

  • Filoe Type in TYPE (IY+9)

Exit:
- 78A4/A5 = starting address
- 78F9/FA = ending address + 1
Registers used:

AF, BC, DE, HL

Error handling:

  • A = 0 Ok

  • A = 9 An address mark was not found

  • A =10 A checksum error

  • A =12 File found but wrong type

  • A =13 File does not exists

  • A =17 BREAK key pressed

The program specified in the FNAM field is transferred from the diskette to the memory.

After successful completion, the start address and the end addresst+1 of the memory area are transferred in the BASIC communication area at address 78A4/A5 and at address 78F9/FA.

This routine only works with files that contain the start address in bytes 12 and 13 of the table of contents and the end address + 1 in bytes 14 and 15, ie not with standard data files.

If a program is saved with the BASIC commands SAVE or BSAVE or by machine programs with the routine SAVE, this entry is made automatically.

The LOAD routine automatically turns the drive on and off and also turns off interrupts.

Example:

...
LD (IY+11),80H          ; select Drive 2
LD HL,DNAM              ; filename to FNAM
CALL 401DH              ; register
LD (IY+9),'B'           ; file type 'B' (binary)
CALL 4041H              ; load program
OR A                    ; error occurred?
JP NZ,400EH             ; yes, to the ERROR routine
EI                      ; enable interrupts again
...
DNAM: DEFM '“GRAFDR”:'

The binary file or machine program “GRAFDR” is transferred from the floppy disk in drive 1 into memory.

Internally called routines: SEARCH, READ