DOS Fn 4b01H: Load Program

                                                         Compatibility: 2.0+ 
 Expects: AX    4b01H
          DS:DX address of an ASCIIZ filespec of the program to load
          ES:BX address of an ExecLoadRec
 Returns: AX    error code if CF is set to CY
          ES:BX some information is returned in the ExecLoadRec
    Info: This allocates memory and loads a program.  It builds a PSP and
          performs all needed segment fixups in preparation for executing
          the code, but does not actually begin execution.

    DS:DX points to an ASCIIZ string in the form...
          If the drive or path is omitted, defaults are assumed.

    ES:BX points to a block of memory prepared as an ExecLoadRec that has
          been filled with the information needed, similar to the needs of
          fn 4b00H (exec).

          On return the ExecLoadRec contains the required entry point
          (lCsIp) and stack address (lSsSp) to use when starting the

   Notes: ■ There must be enough free memory for DOS to load the program.

See Also: Fn 4b00H (execute program)
          Fn 4b03H (load overlay)
          Fn 4b05H (set execution state)
          Process Control Functions
          Program Startup & Exit
          DOS Functions