Difference between revisions of "Operand"

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In the example below, [[JMP]] is the opcode, $1000 is the operand, and the two combined is the instruction.
 
In the example below, [[JMP]] is the opcode, $1000 is the operand, and the two combined is the instruction.
  
  0001:4C 00 10  JMP $1000      ; Moves the execution pointer to $1000.
+
  0001:4C 00 10  JMP $1000      ; Moves the program counter to $1000.
  
 
In this example, [[DEX]] is the opcode, but there is not operand since it is implied from the opcode.
 
In this example, [[DEX]] is the opcode, but there is not operand since it is implied from the opcode.
  
 
  0001:CA        DEX            ; Decrements the X index register.
 
  0001:CA        DEX            ; Decrements the X index register.

Revision as of 11:06, 26 October 2012

An operand is the data portion of a 6502 assembly instruction. This is to be distinguished from the opcode, which specifies the operation to perform.


Examples

In the example below, JMP is the opcode, $1000 is the operand, and the two combined is the instruction.

0001:4C 00 10  JMP $1000      ; Moves the program counter to $1000.

In this example, DEX is the opcode, but there is not operand since it is implied from the opcode.

0001:CA        DEX            ; Decrements the X index register.