Assembly Exam 1

If-Then

IF

conditional branch ENDIF

THEN {block}

ENDIF

If-Then-Else

IF

conditional branch ELSE

THEN {then block}

BRA ENDIF

ELSE {else block}

ENDIF

While

WHILE

conditional branch ENDWHILE

{block}

BRA WHILE

ENDWHILE

Do-Until

DO {block}

UNTIL

conditional branch DO

ENDDO

Extended Addressing Mode

16-bit address given in instruction

ex: ADDA $C210 —→ EA = $C210

Direct Addressing Mode

LSB given in instruction

ex: ADDA $C2 —→ EA = $00C2

Inherit Addressing Mode

No EA to be generated, data is either in processor or not needed

ex: ABA ——→ (A) + (B) → (A)

Immediate Addressing Mode

No EA to be generated, data in instruction

ADDA #$C2 ——→ (A) + $C2 → (A)

Indexed Addressing Mode

X & Y registers as base, provides 1-byte offset

EA = (X or Y) + offset