COAL FT REVIEWER

Central Processing Unit

• Brain of the computer

• Most important component

• Does most of the work

• Performs all types of data processing

Baran Jons Jakob Berzelius

discovered silicon

John Bardeen, Walter Brattain, William Shockley

first transistor was created by

Robert Noyce and Jack Kilby

first working integrated circuit was built by

1. Memory or storage unit

2. Control unit

3. ALU (Arithmetic Logic Unit)

Different Parts of CPU

Memory or Storage Unit

• Can store instructions, data, and intermediate results

• Responsible for transferring information to other units

• Internal storage unit or the main memory

• Size affects speed, power, and performance

• Primary memory

• Secondary Memory

Types of Memory

• fetch

• decode

• execute

• store

Fundamental Functions of the Computer

Single Core CPU

oldest type of CPU, only process one operation at a single time

Dual-Core CPU

contains a single integrated circuit with two cores

Quad-Core CPU

contains two dual-core processors 

Arithmetic Logic Unit (ALU)

• Basic operations of the computers of earlier times are representing and storing numbers

• Mathematical brain

• Digital circuit

• Fundamental building block of the CPU

• Data section (data path)

• Control section

CPU can be divided into 2 sections:

Bus

• Parallel electrical wires with multiple hardware connections

• Communication system that transfers data between components

• address bus

• data bus

• control bus

Three Types of Bus

Address bus

transfers memory addresses from the processor to components

Data bus

carries the data

Control bus

carries control signals

Registers

• Very fast computer memory

• serves as gates

• directed by control unit

• program counter

• instruction registers

• memory address register

• memory data register

• general purpose register

Five registers for in-out signal data storage

Program counter

has the address of the next instruction to be executed from memory

Instruction registers

holds the instruction currently being executed

Memory address register

stores the memory address from which data will be fetched

Memory data register

stores the data being transferred to

General purpose register

store temporary data within the microprocessor

Data Path

• Made of functional components, multipliers or ALUs

• Required to do data processing operations

One Bus Organization

A single bus is used for multiple purposes

Two Bus Organization

to overcome the disadvantage of one bus organization, two buses

In-Bus

the general-purpose register can read data

Out-bus

the general-purpose registers can write data. Here buses get dedicated

Three Bus Organization

three buses, OUT bus1, OUT bus2, and IN bus

Micro-operations

every sub-cycle has one or more shorter operations that must be completed

• fetch cycle

• execute cycle

• interrupt cycle

• indirect cycle

Sub cycles

• memory address register

• memory buffer register

• program counter

• instruction registers

The Fetch cycle: 4 registers

Indirect Cycle

once an instruction is fetched, the next step is to fetch source operands

Execute cycle

numbers of different sequence of micro-operations that can occur

Interrupt Cycle

varies greatly from one machine to another

Sequencing

control unit causes the processor to step through

Execution

the control unit cases each micro-operation to be performed

Clock

control unit ‘keeps time’ in this manner

fetch cycle

causes an instruction to be fetched from memory

Flags

determine the status of the processor and the outcome of previous ALU operations

Control signals from control bus

signals are sent to the control unit via control bus segment of the system bus

Control signals within the processor

– two types: those that cause data to be moved from one register to another, and those that activate specific ALU functions

Control signals to control bus

– two types: control signals to memory, control signals to the I/O modules

Control Signals

Opens gates, allowing the contents of the MAR onto the address bus

Hardwired implementation

control unit is essentially a state machine circuit

Clock

issues a repetitive sequence of pulses

Assembly Language Programming

·        Low-level programming language

·        Specific to a particular computer architecture

·        converted into executable machine code by a utility program referred to as an assembler

·        uses a mnemonic to represent each low-level machine operation or opcode

3 Types of Instruction Statements

·        opcodes mnemonics

·        data sections

·        assembly directives

Opcode mnemonics

symbolic name for a single executable machine language

Data directives

·        define data elements to hold data and variables

·        define the type of data, length and alignment

Assembly directives

• also called ‘pseudo-opcodes

• instructions that are executed by an assembler or assembly time

Symbolic assemblers

let programmers associate arbitrary names with memory locations

Macros

·        sequences of text lines in which variables and constants are embedded

·        often allow macros to take parameters

EDSAC computer (1949)

has an assembler called initial orders with one-letters mnemonics

Nathaniel Rochester (1954)

wrote an assembler for IBM 701

SOAP (symbolic optimal assembly program) (1955)

·        assembly language for IBM 650 (stan poley)

Assembly programming tools

IDE and deploy Java platform

Machine Language

·        Native to a processor

·        Instructions consist of binary code

Assembly Language:

·        A programming language that uses symbolic names to represent operations, registers and memory locations.

Instruction

– each command of a program

Opcode field

stands for operation code, specifies the operation

Operands fields

where to get the source and destination

HLL instruction

– called a ‘statement’. Will be translated to one or more instructions