| Instruction A | Instruction B | Same? | Different? | Comment |
|---|---|---|---|---|
| ori $4,$0,0x8 | ori $4,$0,8 | 0x8 and 8 specify same 16-bit pattern: 0000 0000 0000 1000 | ||
| ori $4,$0,0x32 | ori $4,$0,50 | 0x32 and 26 specify same 16-bit pattern: 0000 0000 0011 0010 | ||
| ori $3,$10,26 | ori $3,$0,26 | the operand registers differ | ||
| ori $9,$10,0x000 | ori $9,$10,0 | 0x000 and 0 specify same 16-bit pattern: 0000 0000 0000 0000 | ||
| ori $10,$9,45 | ori $10,$9,45 | same instruction | ||
| ori $5,$5,0x21 | ori $5,$5,21 | different 16-bit immediate operands |
The destination register can be any general purpose register.
But it makes no sense to use register $0,
because that register always contains all zero bits.
# mistaken attempt to change $0 ori $0,$9,0x32
The assembler part of the SPIM simulator does not write an error message for the above mistaken instruction. But the instruction does not change register zero when executed.
Here is a tiny program that bitwise ORs two patterns.
First one pattern is loaded into register $8 , then
the register is ORed with an immediate operand.
The result goes into register $10 .
Soon we will assemble and run the program. You can do this now, if you want (remember you can use copy-and-paste from this page to your text editor). First, predict the result.
## Program to bitwise OR two patterns
.text
.globl main
main:
ori $8,$0,0x0FA5 # put first pattern into register $8
ori $10,$8,0x368F # or ($8) with second pattern. Result to $10.
## End of file
Here are the two patterns, written both in bit patterns and in hex. Perform the bitwise OR operation. (Do it column-wise with the bits, then translate the answer to hex).
0000 1111 1010 0101 0FA5 0011 0110 1000 1111 368F ------------------- ----