Motorola M68HC11EVBD, User Manual

Page: 57 / 110

OPERATING INSTRUCTIONS
M68HC11EVBU/D 4-11
ASM Assembler/Disassembler
If the assembler tries to assemble at an address that is not in RAM or EEPROM, an invalid
address message "rom-xxxx" is displayed on the terminal CRT (xxxx = invalid address).
Assembler/disassembler subcommands are as follows. If the assembler detects an error in the
new source line, the assembler will output an error message and then reopen the same address
location.
/ Assemble the current line and then disassemble the same address location.
^ Assemble the current line and then disassemble the previous sequential
address location.
<CR> Assemble the current line and then disassemble the next opcode address.
(CTRL)J Assemble the current line. If there isn’t a new line to assemble, then
disassemble the next sequential address location. Otherwise, disassemble
the next opcode address.
(CTRL)A Exit the assembler mode of operation.
Examples:
>ASM 0100<CR>
0100 STX $FFFF >LDAA #55<CR>
Immediate mode addressing, requires #
86 55
before operand.
0102 STX $FFFF >STAA C0<CR>
Direct mode addressing.
97 C0
0104 STX $FFFF >LDS 0,X<CR>
Index mode, if offset = 0 (,X) will not
AE 00
be accepted.
0106 STX $FFFF >BRA C500<CR> Branch out of range message.
Branch out of range
0106 STX $FFFF >BRA 0130<CR>
Branch offsets calculated automatically,
20 28
address required as branch operand.
0108 STX $FFFF >(CTRL)A
Assembler operation terminated.
>
NOTE
In the above example memory locations $0100-$0108 previously
contained $FF data which disassembles to
STX $FFFF
.