Computer Architecture Operation-code encoding techniques

1. Operation(Op) Code
Encoding Techniques

2. Index
Op-Code Encoding
Op-Code encoding techniques
Block-Code Technique
Expanding op-code technique
Huffman Encoding

3. Op-Code Encoding
Binary(0 , 1) pattern is known as op-code
encoding techniques.A processor can execute an
instruction only if it is convert as a binary
sequence. And this converted binary sequence is
Op-code encoding.

4. Op-Code Encoding Techniques
▪ Block-code technique
▪ Expanding op-code technique
▪ Huffman Encoding

5. fgf
Block-Code Technique
▪ If each instruction used the same number of bits than it
is known as block-code techniques
▪ It is a very simple and easy techniques.
3 to 8 Decoder
000 Instruction 1
001 Instruction 2
010 Instruction 3
011 Instruction 4
100 Instruction 5
101 Instruction 6
110 Instruction 7
111 Instruction 8
3 op-code bit

6. Expanding op-code technique
16 bit instruction and 4 bit address field
op-code address field address field
address field
it is 16,3 address field instruction
1 0 1 0 0 1 1 0 0 0 1 1 1 0 0 0

7. 1 0 1 0 0 1 1 0 0 0 1 1 1 0 0 0
1 0 1 0 0 1 1 0 0 0 1 1 1 0 0 0
1 0 1 0 0 1 1 0 0 0 1 1 1 0 0 0
op-code
op-code address
field
address field
op-code op-code op-code address field
op-code op-code op-code op-code
256,2 address field instrution
4096,1 address field instrution
65536, 0 address field
instrution

8. Huffman Encoding
It is a memory saving encoding techniques,where we do
not need same number bits for each instruction.
Fewer bits are used for most frequently used instructions
and more bits for the least frequently used instructions.

9. 23
28
38
62
100
34
1
5
10
13
14 14
7 7
2
5
0
0
0
1
1
0
0
0
0
1
1
1
1
1
Block/ expand encoding
for 5 ins 3*5 =15
for 34 ins. 3*34 = 102
total= 117
Huffman encoding
for 5 ins (10111) 5*5 =
25
for 34 ins (11) 2*34 =
68
total = 93

10. Op-Code Encoding, Huffman Codes
ADVANTAGE:
❏ Minimal number of bits
❏ Memory saving techniques
DISADVANTAGE:
❏ It is a slow technique because it decode instruction bit-by-
bit
❏ Fact is, most decoding is done in parallel
❏ to decode, must have a logical representation of the
encoded tree, and follow branches as we decipher bits