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lw $12, 0x10($13)

The original value in $12 is irrelevant; it is replaced with a value from memory (memory remains unchanged).

Store Word Instruction

The store word instruction, sw, copies data from a register to memory. The register is not changed. The memory address is specified using a base/register pair.

sw   t,off(b)       # Word at memory address (b+off) <— $t 
                    # b is a register. off is 16-bit two's complement.

As with the lw instruction, the memory address must be word aligned (a multiple of four).


Picture of the Problem

Look at registers $12 and $13 and memory (at right). Write the instruction that puts the word 0xFFFFFFFF into memory location 0x0004000C.

  • Register $12 contains 0xFFFFFFFF
  • Register $13 contains 0x00040014
sw $ ,($)

Hint: it is OK to specify the 16-bit offset as a signed decimal integer.