The R-Type Instruction

A typical MIPS instruction is a string of 32 binary digits together. An example of a R-type instruction can look like this: In order to simplify things, the instruction can be segmented as follows: For the R-type instruction, there are six components.

• Operation code
• First source register
• Second source register
• Destination register
• Shift amount
• Function bits

And as you have already guessed it, each segment of bits correspond to one of the above component.

Component	Bit range	Example
Opcode	31st to 26th	000000 01000 00011 00010 00000 100010
First source register	21st to 25th	000000 01000 00011 00010 00000 100010
Second source register	16th to 20th	000000 01000 00011 00010 00000 100010
Destination register	11th to 15th	000000 01000 00011 00010 00000 100010
Shift amount	6th to 10th	000000 01000 00011 00010 00000 100010
Function bits	0th to 5th	000000 01000 00011 00010 00000 100010

The syllabus that will be followed dictates the following function bits and their binary representative:

Function bits	Binary representative
ADD	100000
SUB	100010
AND	100100
OR	100101
SLT	101010

With some decoding, Or simply put,

The I-Type Instruction

An example of a I-type instruction can look like this: But this time, the components are different, as shown below:

Component	Bit range	Example
Opcode	31st to 26th	001000 00001 00110 0000000000001010
Source register	21st to 25th	001000 00001 00110 0000000000001010
Destination register	16th to 20th	001000 00001 00110 0000000000001010
Immediate data	0th to 15th	001000 00001 00110 0000000000001010

With a little decoding, Or simply put,