Question

The following program fails to load the value 8 into $t0. In fact, it creates an exception. Why?

assembly
Copy code
.text
lui $t0, 1001
lw $a0, 0($t0)
li $v0, 1
syscall
li $v0, 10
syscall
.data
.word 8
a. Incorrect memory address
b. Missing syscall instruction
c. Incorrect register usage
d. Invalid data section

Answer 1

The failure to load the value 8 into register $t0 and the resulting exception are due to incorrect memory address manipulation, specifically using an improper immediate value with the lui instruction without a valid base address.

Step-by-step explanation:

The issue with the program lies in incorrect memory address manipulation when attempting to load a value into register $t0. The lui (Load Upper Immediate) instruction is meant to load a 16-bit immediate into the upper half of a 32-bit register, but the error comes from the use of 1001 without a proper base address. It's loading a half-word, and when combined with the lower half loaded by lw (Load Word), it does not point to a valid memory address. This results in an exception because the address formed is not referencing a valid memory location where data is stored.

The correct method would be to load an address that has been properly defined in the data section. Once a valid data section address is used, the program would successfully load the value 8 into the register $t0 using the lw instruction.