DISK - Send a disk command

    DISK "command_string" [<ON|,>Udevice]

The DISK command is used to send special commands to the DOS via the disk drive's command channel. The DISK command is analogous to the following BASIC code:

        OPEN 1,n,15: PRINT#1,"command_string": CLOSE 1

Not all disk drives understand the same commands. Refer to your DOS manual for commands and command syntax for your drive. Note that the drive number, if any, must be included in the command-string.

    DISK "U0>10"                Renumber system drive to 10.
    DISK "U0>V"+chr$(0)         Turn off write verify
    DISK "S0:file" U(n)         Scratch "file" on unit n

DLOAD - Load a BASIC program file from disk

    DLOAD "filename" [,Ddrive] [<ON|,>Udevice]

This command copies a BASIC program from disk into the BASIC program area of the computer. It can then be edited, DSAVEd, or RUN.

Used in program mode, it overlays the current program in memory and begin execution automatically at the first line of the new program. Variable definitions will be left intact, but any open data files and the disk command channel will be automatically closed. This is called CHAINING.

See also RUN. Use BLOAD to load binary or machine language data.

    DLOAD "myprogram"           Searches the default system disk drive
                                for the BASIC program "myprogram",
                                loads it, and relinks it.
    DLOAD (F$),U9               LOADs a program whose name is in F$
                                from disk unit 9.

DMA - Perform a DMA operation

    DMA command [,length,source(l/h/b),dest(l/h/b),subcmd,mod(l/h) [,...]

[*** THIS COMMAND IS SUBJECT TO CHANGE ***]

The DMA command defines and executes a Direct Memory Access operation. The parameters are used to construct a DMA list, which is then passed to the DMA processor for execution. Refer to the DMA chip specification for details. Chained DMA commands are not allowed, but multiple DMA commands can be given and the DMA handler will set up and execute each one, one at a time. Refer to the system memory map to find out where things are.

Because this command directly accesses system memory, extreme care should be taken in its use. Changing the wrong memory locations can crash the computer (press the reset button to reboot).

    DMA 3, 2000, ASC("+"),0,    DEC("800"),O        Fill screen with '+'
    DMA 0, 2000, DEC("800"),0,  DEC("8000"),1       Copy screen to $18000