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The 68kasm Assembler

An assembler is a software program that reads assembly code and directives and produces executable machine code. We will use the 68KASM assembler in this and the next CLAB.

Use a text editor to enter the following code into a new file clab51s.s:

*                               clab51s.s
        ORG     $0
        DC.L    $8000           Stack pointer value after a reset
        DC.L    START           Program counter value after a reset


        ORG     $2000           Start at location 2000 Hex

START   move.w  #$2468,d0       move $2468 into register d0
        add.w   #1,d0           add 1 to do
        BREAK                   tell the simulator to BREAK

The syntax will be explained below.

In a terminal window, cd into the directory containing your new file clab51s.s and assemble it by typing:

68kasm -l clab51s.s

If all was successful the software will say so and produce two files:

clab51s.lis - a listing showing the assembled machine code.

clab51s.h68 - a (text) file of 68000 s-records which BSVC can load and execute.

Take a look at both files using a text editor.

If any errors occured, correct them and make sure these files have been created before proceeding.

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