In: Computer Science
Suppose the opcode of an MIPS instruction is 12 in decimal, and the rest of the machine code is 23483DB in hexadecimal (from high-order bit to low-order bit). What is the instruction? When showing the registers, use names (e.g. $t0, $s2) instead of indices (e.g $8, $17). For branch instructions, show offset in place of label, e.g. beq $t1, $t2, 92.
Hexadecimal     Binary
    0           0000
    1           0001
    2           0010
    3           0011
    4           0100
    5           0101
    6           0110
    7           0111
    8           1000
    9           1001
    A           1010
    B           1011
    C           1100
    D           1101
    E           1110
    F           1111
Use this table to convert from hexadecimal to binary
Converting 23483DB to binary
2 => 0010
3 => 0011
4 => 0100
8 => 1000
3 => 0011
D => 1101
B => 1011
So, in binary 23483DB is 10001101001000001111011011
opcode = 12
so, first 6 bits are 001100
instruction in binary is 001100 10001101001000001111011011
=>  00110010001101001000001111011011
=>  001100 10001  10100  1000001111011011
=>  opcode rs rt immediate
=>  ANDI   $s1    $s4    immediate
Converting 1000001111011011 to hexadecimal
1000 => 8
0011 => 3
1101 => D
1011 => B
So, in hexadecimal 1000001111011011 is 0x83DB
so, instruction is andi $s4, $s1, 0x83DB
Answer:
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andi $s4, $s1, 0x83DB