Topic 3 subtopic 1 : R type and addressing

Topic 3 Subtopic 1:Register Type(R-type)

There are three types of instruction format:Register Type (R-type),Immediate type(I-type) and Jump type(J-type). Of the three formats, the R-type is the most complex.

   

B31-26	B25-21	B20-16	B15-11	B10-6	B5-0
opcode	register s	register t	register d	shift amount	function

opcode

Opcode is short for "operation code". The opcode is a binary encoding for the instruction.
All R-type instruction use opcode 000000.

register s

Register s is source register specifier.The source register is the register that holds one of the arguments of the operation.

register t

Register t is target register specifier.It is the second source register.
  
register d

Register d is destination register specifier.Destination register is the register where the result of the operation is stored.

shift amount 

The amount of bits to shift. Used in shift instructions. 


function

An additional 6 bits used to specify the operation, in addition to the opcode.


Register addressing 

Register addressing is the simplest addressing mode.

 

where; $t0=rd
            $t1=rs
            $t2=rt


thus : $t0=$t1+$t2






TONG WENG SENG
B031210084