Topic 3 Subtopic 2 : I type and addressing

Immediate Type (I-Type)

• An immediate operand,branch instructions,load and store instructions are included in the instructions.
• In the MIPS architecture,all memory access are handled by the critical processor,so coprocessor load and store instruction are included in this group.
• An instruction with an immediate constant has the

          SPIM form:

          Opcode               Operands               Comment
            Addi                   $4,$7,78               # $4=$7 + 78

• Example:

• Encoding of the 32 bits:

         – Opcode is 6 bits.
         – Since we have 32 registers, each register “name” is 5 bits.
         – This leaves 16 bits for the immediate constant.

•  All opcodes except 000000,00001x,and 0100xx .

Immediate addressing

• Immediate addressing means that one operand is a constant within the instruction itself.
• Immediate addressing has the advantage of not requiring an extra memory access to fetch the operand, but the operand is limited to 16 bits in size.
• The jump instruction format can also be considered an 
• example of immediate addressing, since the destination is 
• held in the instruction.
• For example ,use 'PI' as a constant 3.14 within the code.

       



LIM ZHEW SHENG
B031210379