Computer Science 210 Computer Organization

1
Computer Science 210Computer Organization

• Translating from Assembly Language
• To Machine Code

2
Translating Instructions

• Each instruction translates to a 32-bit word in
  memory
• The operator and operands are translated to bit
  strings and assigned to spots in the memory word
  according to the instructions format type

3
Instruction Formats

• R-type for arithmetic operations with registers
• I-type for data transfer operations and
  conditional branches
• J-type for unconditional branching operations

4
R-Type Format
add t0, s1, s2
5
R-Type Format
add t0, s1, s2
0
17
18
8
0
32
6
R-Type Format
add t0, s1, s2
0
17
18
8
0
32
000000
10001
10010
01000
00000
100000
7
R-Type Format
add t0, s1, s2
0
17
18
8
0
32
000000
10001
10010
01000
00000
100000
op
rs
rt
rd
shamt
funct
Opcode first second
destination shift function
register register register
amount code
8
I-Type Format
lw t0, 32(s3) t0 A8
9
I-Type Format
lw t0, 32(s3) t0 A8
35
19
8
32
10
I-Type Format
lw t0, 32(s3) t0 A8
35
19
8
32
100011
10011
01000
0000000000100000
11
I-Type Format
lw t0, 32(s3) t0 A8
35
19
8
32
100011
10011
01000
0000000000100000
op
rs
rt
16 bit address offset
Opcode first destination
address offset
register register
12
J-Type Format
j endif endif 45
13
J-Type Format
j endif endif 45
2
45
14
J-Type Format
j endif endif 45
2
45
000010
00000000000000000000101101
15
J-Type Format
j endif endif 45
2
45
000010
00000000000000000000101101
op
26 bit address offset
Opcode
address offset