LOAD

Description:

This routine LOADs data bytes from any input device directly into the memory of the Commodore 64. It can also be used for a verify operation, comparing data from a device with the data already in memory, while leaving the data stored in RAM unchanged.

The accumulator (.A) must be set to 0 for a LOAD operation, or 1 for a verify. If the input device is OPENed with a secondary address (SA) of 0 the header information from the device is ignored. In this case, the X and Y registers must contain the starting address for the load. If the device is addressed with a secondary address of 1, then the data is loaded into memory starting at the location specified by the header. This routine returns the address of the highest RAM location loaded.

Before this routine can be called, the KERNAL SETLFS, and SETNAM routines must be called.

How to Use:

1. Call the SETLFS, and SETNAM routines. If a relocated load is desired, use the SETLFS routine to send a secondary address of 0.
2. Set the A register to 0 for load, 1 for verify.
3. If a relocated load is desired, the X and Y registers must be set to the start address for the load.
4. Call the routine using the JSR instruction.

EXAMPLE:

         ;LOAD A FILE FROM TAPE
         LDA  #DEVICE1     ;SET DEVICE NUMBER
         LDX  #FILENO      ;SET LOGICAL FILE NUMBER
         LDY  CMD1         ;SET SECONDARY ADDRESS
         JSR  SETLFS
         LDA  #NAME1-NAME  ;LOAD A WITH NUMBER OF CHARACTERS IN FILE NAME
         LDX  #<NAME       ;LOAD X AND Y WITH ADDRESS OF
         LDY  #>NAME       ;FILE NAME
         JSR  SETNAM
         LDA  #0           ;SET FLAG FOR A LOAD
         LDX  #$FF         ;ALTERNATE START
         LDY  #$FF
         JSR  LOAD
         STX  VARTAB       ;END OF LOAD
         STY  VARTAB+1
         JMP  START
 NAME    .BYT 'FILE NAME'
 NAME1   ;