Introduction to Programming - (C Language) - Unit : 1 - Introduction to Programming and Problem Solving - Basics

 

WHAT IS COMPUTER?

“A computer is an electronic programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations.”

 

COMPUTER HISTORY

 The first calculating device is “ABACUS” invented by Chinese in 3500 BC. Scottish Scientist

‘John Napier’ invented a device. “Napier Bones” .

Blasé Pascal, the French mathematician invented the “Adding machine” simply for additions and subtractions.

Gottfried Leibniz, the German Scientist implemented the Adding machine and made a new

machine ‘ Leibniz Machine’.

 Charles Babbage

 

He was a Professor of Mathematics. He invented a machine called ‘Differential Engine’ in 1822. After he implemented it and found a new machine called ‘Analytical Engine’ in 1832. He is called the “Father of Computers”

 

The First Computer is ENIAC ( Electronic and Numerical Integrator and Calculator). It was developed by John Prosper Eckert and John W. Mauchl in 1945.

 

The later developed Computers are MARK–I EDVAC, UNIVAC, LEO , IBM – 650, UNIVAC – I, IBM – 360 Series, CDC – 1604 etc.

 

Computer Generations

 

 

Generation	Period	Technology Used
First	1946- 55	Vacuum Tubes
Second	1956-65	Transistors
Third	1966-75	I.C ( Integrated Circuits)
Fourth	1976-85	V.L.S.I.C (Very Large Scale Integrated Circuits )
Fifth	1985 onwards	A.I ( Artificial Intelligence)

Basic Organization Of A Computer

 

Computer takes data (Input) from the Input devices and processing the data under the instruction given by the user and finally gives the result (Output) through the Output devices.

 

Computer Basic Structure

The basic organization of a computer involves several key components and their interactions, which collectively enable a computer to process and store data. Here are the fundamental components and their roles in a computer's organization:

 

Central Processing Unit (CPU):

The CPU is the brain of the computer, responsible for executing instructions and performing calculations.

It consists of two main units: the Control Unit (CU), which manages the execution of instructions, and the Arithmetic Logic Unit (ALU), which performs mathematical and logical operations.

The CPU fetches instructions from memory, decodes them, and executes them sequentially.

 

Memory:

Computers have various types of memory, including:

RAM (Random Access Memory): This is volatile memory used for temporarily storing data and program instructions that the CPU is actively using. It allows for fast read and write operations but loses its data when the computer is powered off.

ROM (Read-Only Memory): This is non-volatile memory that stores essential instructions and data that don't change, such as the computer's firmware or BIOS.

Secondary Storage: This includes devices like hard drives (HDDs) and solid-state drives (SSDs), used for long-term storage of data and programs. Unlike RAM, secondary storage retains data even when the computer is turned off.

 

Input Devices:

Input devices allow users to interact with the computer by providing data and instructions. Common examples include keyboards, mice, touchscreens, and microphones.

 

Output Devices:

Output devices present information or results to the user. Common examples include monitors, speakers, printers, and headphones.

 

Motherboard:

The motherboard is the main circuit board that houses and interconnects the CPU, memory, storage devices, input/output ports, and other essential components. It provides the electrical pathways for data transfer between these components.

 

Bus System:

Buses are pathways that transfer data and control signals between various computer components. Common buses include the data bus (for transferring data), the address bus (for specifying memory locations), and the control bus (for managing data flow and coordination).

 

Power Supply Unit (PSU):

The PSU supplies electrical power to the computer's components. It converts AC (alternating current) from a wall outlet into DC (direct current) usable by the computer's internal components.

Expansion Slots and Ports:

 

Expansion slots allow for the installation of additional hardware components like graphics cards, sound cards, and network cards.

Ports provide external connectivity and include USB ports, audio jacks, Ethernet ports, and video connectors (e.g., HDMI, DisplayPort).

 

Operating System (OS):

The operating system is system software that manages computer hardware and software resources. It provides a user-friendly interface, manages processes, handles file storage, and facilitates communication between hardware and software.

 

Software:

Software includes applications, programs, and the operating system itself. It consists of instructions and data that the CPU processes to perform specific tasks.

 

ALU (ARTITHMETIC AND LOGICAL UNIT)

 

The Arithmetic Logic Unit (ALU) is a critical component of the Central Processing Unit (CPU) in a computer. It is responsible for performing arithmetic and logical operations on data. Let's dive into a detailed explanation of the ALU:

 

1. Purpose and Function:

The ALU's primary function is to perform mathematical calculations and logical operations on binary data. These operations are the fundamental building blocks of computation in a computer.

 

2. Arithmetic Operations:

The ALU can execute various arithmetic operations, including:

Addition: Adding two binary numbers together.

Subtraction: Subtracting one binary number from another.

Multiplication: Performing binary multiplication.

Division: Performing binary division.

Increment and Decrement: Adding or subtracting one from a binary number.

 

3. Logical Operations:

The ALU also handles logical operations, which manipulate bits or binary data in various ways. Common logical operations include:

AND: Performs a bitwise AND operation, resulting in 1 only if both input bits are 1.

OR: Performs a bitwise OR operation, resulting in 1 if at least one input bit is 1.

NOT: Inverts each bit, turning 0s into 1s and vice versa.

XOR (Exclusive OR): Performs a bitwise XOR operation, resulting in 1 if the input bits are different.

 

4. Data Size:

ALUs are designed to handle a specific word size or data size, which determines the maximum size of the data they can process in a single operation. For example, a 32-bit ALU can perform operations on 32-bit binary numbers.

 

5. Registers:

The ALU works closely with CPU registers, which are small, high-speed storage locations within the CPU. Registers store the operands (input values) for ALU operations and hold the results temporarily.

Common registers include the Accumulator (for storing intermediate results), the Operand Register (for holding data to be processed), and the Result Register (for storing the output of ALU operations).

 

6. Flags and Status Bits:

The ALU often sets various flags or status bits in the CPU's status register to indicate the outcome of operations. Common flags include:

Zero Flag: Set if the result of an operation is zero.

Carry Flag: Set if an operation produces a carry out of the most significant bit.

Overflow Flag: Set if an operation generates an overflow or underflow condition.

Sign Flag: Indicates the sign of the result (positive or negative).

 

7. Control Unit Interaction:

The ALU operates under the control of the CPU's Control Unit. The Control Unit sends control signals to the ALU, specifying the operation to be performed (e.g., addition, subtraction, logical AND) and which registers to use as operands.

 

8. Pipelining and Parallelism:

In modern CPUs, ALUs often employ techniques like pipelining and parallelism to improve performance. Pipelining allows multiple instructions to be processed concurrently in different stages of the ALU, while parallelism enables simultaneous execution of multiple operations.

 

9. Speed and Performance:

ALUs are designed to perform operations quickly, as their speed impacts the overall performance of the CPU. Improving ALU performance is a key aspect of CPU design.