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Assembly Language Review

A Basic Processor

CS 21 - Computer Organization and Assembly Language Programming Lecture 13 A Basic Processor University of the Philippines - Diliman College of Engineering Department of Computer Science


Assembly Language Review

Outline

1

Assembly Language Review

2

A Basic Processor

A Basic Processor


Assembly Language Review

Outline

1

Assembly Language Review

2

A Basic Processor

A Basic Processor


Assembly Language Review

A Basic Processor

Refresher

Assembly Language just one level away from machine language directly translated by assembler to machine language via lookup tables


Assembly Language Review

MIPS Instruction Types

There are 3 types of instructions in MIPS: R Type R stands for register-to-register examples include add, addu,sub, subu, nor, and, xor

I Type I stands for immediate examples include addi, andi, xori

J Type I stands for jump examples are j and jal

A Basic Processor


Assembly Language Review

R-Type

Notes: opcode - 6 bits - always 000000 rs - 5 bits - depends on the operand register rt - 5 bits - depends on the operand register rd - 5 bits - depends on the destination register sa - 5 bits - used in shift operations, 00000 otherwise function - 6 bits - depends on the operation/function

A Basic Processor


Assembly Language Review

I-Type

Notes: opcode - 6 bits - depends on the operation/function rs - 5 bits - depends on the operand register rt - 5 bits - depends on the operand register immediate - 16 bits - contains the immediate value

A Basic Processor


Assembly Language Review

A Basic Processor

J-Type

Notes: opcode - 6 bits - 000010 for j, 000011 for jal target - 26 bits - distance of target/destination from current j/jal instruction(in number of instructions)


Assembly Language Review

Outline

1

Assembly Language Review

2

A Basic Processor

A Basic Processor


Assembly Language Review

A Basic Processor

In the beginning...

Assume that we have the instruction add $t1, $t2, $t3


Assembly Language Review

A Basic Processor

In the beginning...

Assume that we have the instruction add $t1, $t2, $t3 What would we need to execute this instruction?


Assembly Language Review

Building a processor

A Basic Processor


Assembly Language Review

Building a processor

Is this correct?

A Basic Processor


Assembly Language Review

Building a processor

A Basic Processor


Assembly Language Review

Building a processor

How about the other instructions?

A Basic Processor


Assembly Language Review

Building a processor

A Basic Processor


Assembly Language Review

Building a processor

A Basic Processor


Assembly Language Review

Building a processor

A Basic Processor


Assembly Language Review

Building a processor

A Basic Processor


Assembly Language Review

Memories

A Basic Processor


Assembly Language Review

Memories

technically, not part of the processor where we load instructions and load/store data

A Basic Processor


Assembly Language Review

Immediate Instructions

A Basic Processor


Assembly Language Review

A Basic Processor

Immediate Instructions

need for multiplexer before ALU since not all operands would come from register file(immediate operations: addi, subi, etc) need for extender since immediate operands from instructions are not yet 32-bits


Assembly Language Review

Loads

A Basic Processor


Assembly Language Review

A Basic Processor

Loads

need for multiplexer before register since not all values to be written to register file would come from ALU: some would come from data memory(loads)


Assembly Language Review

Program Counter

A Basic Processor


Assembly Language Review

A Basic Processor

Program Counter

need for multiplexer before Program Counter since next value of PC has two possible sources


Assembly Language Review

Program Counter: Next instruction

A Basic Processor


Assembly Language Review

A Basic Processor

Program Counter: Next instruction

dedicated adder which adds 4 to the current value of PC, output used by the multiplexer when program flow is normal(instruction executed not branch or jump)


Assembly Language Review

Program Counter: Jump/Branch

A Basic Processor


Assembly Language Review

A Basic Processor

Program Counter: Jump/Branch

dedicated adder which computes the value to which the PC would be set in case of branch or jump: one operand is the current PC, the other comes from the instruction itself

Lecture13  
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