Question

Encode the following instruction

(1) identify the instruction format that will be used,

(2) indicate the values of each of the fields for that format in decimal,

(3) convert each of these decimal val- ues to binary

4) represent the entire instruction as one hexadecimal value.

subu $t3,$v1,$s2

Answer 1

subu $t3,$v1,$s2

1)
subu $t3,$v1,$s2
This is an R-type instruction

2)
opcode  ->  000000
rs      ->  $v1 ->  3
rt      ->  $s2 ->  18
rd      ->  $t3 ->  11
shamt/shift ->  0
funct   ->  SUBU    ->  19

3)
3 in binary is 00011
18 in binary is 10010
11 in binary is 01011
19 in binary is 100011
so, instruction in binary is 000000    00011  10010  01011  00000  100011
Instruction in binary:  00000000011100100101100000100011

4)
Converting 00000000011100100101100000100011 to hexadecimal
0000 => 0
0000 => 0
0111 => 7
0010 => 2
0101 => 5
1000 => 8
0010 => 2
0011 => 3
So, in hexadecimal 00000000011100100101100000100011 is 0x00725823
Instruction in hexadecimal: 0x00725823