& compares every bit

• 0 and 0 = 0
• 0 and 1 = 0
• 1 and 0 = 0
• 1 and 1 = 1

0|0|0|1|0|0|0|1 -|-|-|-|-|-|- 0|0|0|1|0|1|1|0 -|-|-|-|-|-|-

|| operates in the following way

• 0 or 0 = 0
• 0 or 1 = 1
• 1 or 0 = 1
• 1 or 1 = 1

Xor works in the following way

• 0 xor 0 = 0
• 0 xor 1 = 1
• 1 xor 0 = 1
• 1 xor 1 = 0

Xor being the negated version of or

Bitwise Logical Instructions

How to implement NOT using NOR?

• Using $zero as one of the input operands
• It is included in some implementations of MIPS as a pseudo instruction

ADD $target, $source1, $source2

The key letter I may be added in order to add an intermediate. The key letter U may be used in order to make it unsigned

Memory Operands

• memory contains both data and instructions
• Memory can be viewed as a large array of bytes
• The address of a variable or instruction is its offset from the beginning of memory

g = h + A[5]

• lets say g and h are associated with the registers $s1 and $s2 respectively. Let's also say that the base address of A is associated with register $s3

lw $t0, 20($s3) #load the element at a 20 byte offset from $s3
add $s1, $s2, $t0