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Instructions for using the JLOAD.LDR resident-program loader

  1. The program to be made resident must contain a unique identifier used to determine whether the program is already resident in memory. The identifier must be the fourth byte of the program. For example:
START:: jmp   INIT
ID:     db    08h  ; Identifier
INIT:   mov .....  ; The program itself
        .
        .
        .
  1. Assemble the program with M80, then link it with LINK using the [op] option. For example:
M80 DRIVER.ERL=DRIVER.MAC
LINK DRIVER.ERL [op]

When LINK has finished, a file with the .PRL extension will appear on the disk.

  1. The resulting .PRL file must be combined with the JLOAD.LDR resident-program loader using SID. From within SID, load JLOAD.LDR, then load the resident program (the .PRL file) at address 167h. For example:
A>sid

­#ijload.ldr
­#r
­#idriver.prl
­#r167

The loader and the program to be loaded are now together in memory, forming the final program, which must be saved to disk with the CP/M SAVE command. The amount to save can be determined by examining the memory contents in SID. Since the .PRL file ends with a large number of hexadecimal 1A bytes, the end of the program is fairly easy to locate. Once it is clear how much must be written to disk, exit SID (CTRL-C) and save the final program with a .COM extension. For example:

A>save <n> driver.com