Computer Instructions: Lecture Notes

Computer Instructions: Number & Length of Operands

An instruction may include no operands (just the opcode), $1$ operand, $2$ operands, or even $3$ operands:

Opcode                                                
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
| 1 | 0 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+

   Opcode                             Operand #1                 
+---+---+---+---+    +---+---+---+---+---+---+---+---+---+---+---+---+
| 1 | 0 | 1 | 1 |    | 0 | 1 | 1 | 0 | 0 | 0 | 0 | 1 | 1 | 0 | 1 | 0 |
+---+---+---+---+    +---+---+---+---+---+---+---+---+---+---+---+---+

     Opcode                 Operand #1                   Operand #2       
+---+---+---+---+    +---+---+---+---+---+---+    +---+---+---+---+---+---+
| 1 | 0 | 1 | 1 |    | 0 | 1 | 1 | 0 | 0 | 0 |    | 0 | 1 | 1 | 0 | 1 | 0 |
+---+---+---+---+    +---+---+---+---+---+---+    +---+---+---+---+---+---+