Motorola 68000 - Page 19

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The 68000's Instruction Set
CLR Clear an operand
Operation: [destination] ← 0
Syntax: CLR <ea>
Sample syntax: CLR (A4)+
Attributes: Size = byte, word, longword
Description: The destination is cleared  loaded with all zeros. The CLR in-
struction can't be used to clear an address register. You can use
SUBA.L A0,A0 to clear A0. Note that a side effect of CLRs imple-
mentation is a read from the specified effective address before the
clear (i.e., write) operation is executed. Under certain circum-
stances this might cause a problem (e.g., with write-only memory).
Condition codes: X N Z V C
- 0 1 0 0
Source operand addressing modes
CMP Compare
Operation: [destination] - [source]
Syntax: CMP <ea>,Dn
Sample syntax: CMP (Test,A6,D3.W),D2
Attributes: Size = byte, word, longword
Description: Subtract the source operand from the destination operand and
set the condition codes accordingly. The destination must be a
data register. The destination is not modified by this instruction.
Condition codes: X N Z V C
- * * * *