Motorola M68705EVM User Manual page 44

El
ASM
Assembler/Disassembler
ASM
3.6.1 Assembler/Disassembler
ASM <address>
where <address> is the starting address for the assembler operation.
The assembler/disassembler is an interactive assembler/editor in which the source program
is not saved. Each source line is converted into the proper machine language code and is
stored in memory on a line-by-line basis at the time of entry. In order to display an instruction,
the machine code is disassembled and the instruction mnemonic and operands are
displayed. All valid opcodes are converted to assembly language mnemonic. All invalid
opcodes return a Form Constant Byte (FCB) conversion.
The ASM command allows the user to create, modify, and debug MC6805 MCU code. No
provision is made for line numbers or labels.
Assembler input must have exactly one space between the mnemonic and the operand.
There must be no space between the operand and the index specification (,X) except in the
case of indexed no offset. Assembler input must be terminated by a carriage return. No
comments, etc., are allowed after the instruction input. Examples are as follows:
a.
>LDA O,X
b. >STA 10,X
c.
>.A.S.BA
d.
>CQMX
e.
>CMP
2QQ
After each new assembler input line, the new line is disassembled for the user before
stepping to the new instruction. The new line may assemble to a different number of bytes
than the previous one.
For Branch if High or Same (BHS)/Branch if Carry Clear (BCC) mnemonics, disassembly
displays the BCC mnemonic. For Branch if Lower (BLO)/ Branch if Carry Set (BCS)
mnemonics, disassembly displays the BCS mnemonic.
Branch address offsets are automatically calculated by the assembler, thus the address is
inputted as the operand rather than an offset value.
EVALUATION MODULE USER'S MANUAL
3-10
MOTOROLA
M68705EVM