Question

Q: Assistance in understanding and solving this example on Digital Design and Computer Architecture with the steps of the solution to better understand, thanks.

a) The fact that several MIPS instructions (collectively called R-type) follow the

same format:
instruction mnemonic, destination register, first source register, second source register
is a reflection of:

Design Principle 4 not the right answer

Design Principle 3

Design Principle 2

Design Principle 1

b) Which of the four instructions given as choices, correctly matches the description: "this instruction will write the value inside memory location addressed by 24 (that's the decimal number 24) into the register $t2"?.

lw $t2, 0x18($0)

sw $t2, 0x24($0)

lw $t2, 0x24($0)

sw $t2, 0x18($0) not the right answer

c) Which of the four instructions given as choices, correctly matches the description: "this instruction will write the value inside $t5 into memory location addressed by 0x30 (note that the 0x prefix means the number is in hexadecimal format)"?.

lw $t5, 48($0)

lw $t5, 0x30($0)

sw $t5, 48($0)

sw $t5, 30($0) not the answer

Answer 1

Answer (a):

Design Principle 2

Design Principle 2 have conflict to keep all instructions the same length and desire for a single instruction format

Answer (b):

lw $t2, 0x18($0)

It means $t2 = Memory[$0 + 18]

(Note: Because hexadecimal equivalent of 24 is 0x18)

Answer (c):

sw $t5, 48($0)

It means Memory[$0 + 48] = $t5

(Note: Because decimal conversion of 0x30 is 48).

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