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4.3.3
Entering Branch and Jump Addresses
When entering a source line containing a branch instruction (BRA, BGT, BEQ, etc) do not enter
the offset to the branch's destination in the instruction operand field. The offset is calculated by
the assembler. The user must append the appropriate size extension to the branch instruction.
To reference a current location in an operand expression use the asterisk (*) character.
EXAMPLES
0000D000
0000D000
0000D000
0000D000
In the case of forward branches or jumps, the absolute address of the destination may be
unknown as the program is being entered. The user may enter an asterisk (*) for branch to self in
order to reserve space. After the actual address is discovered, the line containing the branch
instruction can be re-entered using the correct value. Enter branch sizes ''B'' or ''W'', as opposed to
''S'' and ''L''.
4.3.4
Assembler Output/Program Listings
Use the MD (Memory Display) command with the ;DI option to obtain a listing of the program.
The MD command requires the starting address and a line count or ending address to be entered
in the command line. When the ;DI option is executed with a line count, the number of
instructions disassembled and displayed is equal to the line count.
Note again, that the listing may not correspond exactly to the program as entered. As discussed in
paragraph 4.2.1.3, the disassembler displays in signed hexadecimal any number it interprets as an
offset of an address register; all other numbers are displayed in unsigned hexadecimal.
M68CPU32BUG/D
6000BF68 BRA *-4096
60FE
BRA.B *
4EF90000 D000
4EF00130 0000D000 JMP (*,A0,D0)
4-12
ASSEMBLER/DISASSEMBLER
JMP *
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