Computer Basics: Data, CPU, and Characteristics

Unit 1: Software Construction Essentials

Data and Information

• Data constitutes raw, unorganized facts and figures including numbers, symbols, characters, words, codes, and graphs
• Information is processed data, relating to a context and having meaning, i.e. "Raju is an 18 year old boy"
• Data processing is when a computer accepts data and produces information

Characteristics of Computers

• Speed is a defining feature
• Computers deliver Accuracy
• Huge Storage capacity is part of computers functionality
• Offer Versatility; the ability to adapt to different jobs
• Demonstrate Diligence; computers do not feel boredom while performing repetitive tasks over time

Disadvantages of Computers

• Exhibit a Lack of IQ
• Cannot make decisions

Block Diagram of a Computer

• A computer comprises an Input Unit, Central Processing Unit (CPU), Storage Unit, and Output Unit
• The CPU includes the Control Unit, Arithmetic Logic Unit (ALU), and Registers
• The Storage Unit has Primary Storage and Secondary Storage

Input and Output Units

Input Unit

• Formed upon connection of an input device to a computer
• Feeds data into the computer to be processed

Output Unit

• Formed when an output device connects to the computer
• Displays the result after processing

CPU (Central Processing Unit)

• Referred to as the 'Brain of Computer'
• Subdivided further into the Arithmetic Logic Unit (ALU), Control Unit, and Registers

ALU (Arithmetic and Logic Unit)

• Executes all arithmetic operations (addition, subtraction, multiplication, division, etc.)
• Executes logical operations (less than, greater than)

Control Unit

• Manages all processes within the computer
• Generates control signals for operations

Registers

• Small memory cells inside the CPU
• Temporarily store intermediate results

Main Memory

• Stores necessary data for data processing
• Results are also saved in this unit until transferred to the output unit

Input Devices

• Used to input data into computer, converting it from human to computer readable form and allowing human readable format
• The keyboard is commonly used, with a QWERTY layout for text input, available in wired and wireless options
• The mouse is a pointing device used to select items when the cursor reaches them, available in wired and wireless options
• The scanner digitizes images/documents and inputs the result into the computer
• Microphone receives sound and inputs to the computer
• OMR (Optical Mark Reader) is for objective tests using special sheets; answer sheets can be valued after reading the sheet
• A barcode reader scans codes as alternate dark/white bars, decodes item details, and inputs data

Output Devices

• These convert data from computer to human readable form producing soft or hard copies
• A printer produces hard copy output on paper. There are impact and non-impact printers, for examples dot matrix, inkjet, and laser printers
• A monitor produces soft copy output, termed VDU (Visual Display Unit) in various types such as LCD/LED
• A speaker is an output device that generates sound
• A projector displays images/videos on a large surface
• A plotter interprets computer commands to create line drawings with automated pens

Storage Types

• Computer Memory is used to store data, information, and instructions, acting as a storage unit where data is processed
• Bit is the smallest memory unit, whether 0 or 1
• A Nibble is a collection of 4 bits
• A Byte is a collection of 8 bits

Units of Computer Memory

• 1 Byte is 8 bits
• 1 KB(Kilobyte) is 1024 Bytes
• 1 MB(Megabyte) is 1024 KB
• 1 GB(Gigabyte) is 1024 MB
• 1 TB(Terabyte) is 1024 GB
• 1 PB(Petabyte) is 1024 TB

Types of Computer Memory

• Divide into Primary and Secondary memory

Primary Memory

• It is the actual memory that computer uses
• The CPU directly fetches data from primary memory

Secondary Memory

• Serves as additional memory, physically separate from the main system
• Examples include hard disks, flash memory, CDs, and DVDs

Primary Memory Types

• RAM (Random Access Memory) can read and write data into, but is volatile so data is lost goes if power cycles. DRAM & SRAM are types of RAM
• ROM (Read-Only Memory) can only read data from. EPROM, EEPROM & PROM are categories

RAM Volatility

• RAM is called volatile because the stored data is lost when the power is switched off

Need for Secondary Memory

• Primary memory is volatile, secondary is permanent
• Secondary memory is able to store huge amounts of data
• Cost per bit of secondary memory is low

Number System

• The quantity of unique symbols used in it dictates the 'base' of a base numbering system
• The binary base numbering system uses 0/1 and has base 2; computers use this numbering system internally
• An octal base numbering system uses 0-7; has base 8
• A Hexadecimal base numbering system uses 0-9 and A-F(10-15) and has base 16
• Decimal has base 10, using 0-9 and is conveniently used for human interface interactions

Conversion to Decimal

• Conversion from binary, octal, and hexadecimal

Conversion from Decimal

• Transform from decimal to binary, octal, and hexadecimal is a function performed by computers efficiently

Conversion From Binary to Octal

• Bits are grouped from LSB to MSB, then number of each group is written

Conversion From Binary to Hexadecimal

• Each group should contain exactly 4 bits

Conversion From Octal to Binary

• Using shortcut method

Conversion From Hexadecimal to Binary

• Used using shortcut method

1's Complement

• To get 1's complement of a number, invert all bits (swap 0 to 1 and 1 to 0)

2's Complement

• In order to get the 2's complement of a number, first identify the 1's complement number of a binary; next add 1 to the LSB

Short Cut Method for finding the 2's Complement

• Invert all bits followed by the first '1' from the right

Sign-Magnitude Representation

• Sign-Magnitude involves using the MSB to indicate the sign; 0 for positive, 1 for negative in an 8 bit stream

One's Complement Representation

• If the number is +ve, The 8-bit number itself is the representation
• If the number is -ve, find the 1's complement of 8 bit number

Two's Complement Representation

• If the number is +ve, The 8-bit number itself is the representation
• If the number is -ve, find the 2's complement of 8 bit number

Algorithm and Flowchart

• Algorithm is the step by step instructions to solve problems
• A flowchart is the pictorial representation of the algorithm
• Includes terminal shapes to show start and stop
• Input/Output shapes to show data flow
• Decision represents test conditions that result in True or False
• Processes represents operations run upon data
• And Connectors which piece together the logic in a diagram

Unit 2: Operating Systems and Computer Networks

Operating System (OS)

• A set of programs acting as an interface between the user and computer to ensure convenient computer use with examples such as Windows, Linux, Android, Mac OS, and iOS

Main Operating System Functions

• Process Management
• Memory management
• File Management
• Device Management

Different Types of Operating Systems

• Batch, Multiprogramming, Multitasking, Real Time, Distributed, and Mobile Operating Systems

Computer Network

• An interconnected collection of computers facilitating mutual communication

Computer Networking Needs

• Resource sharing
• Communication
• Reliability
• Reduced costs

Different Types of Networks by coverage:

• Personal Area Network (PAN) connects devices around a single person
• Local Area Network (LAN) exists within a room, building or campus
• Metropolitan Area Network (MAN) spans a city with 100KM radius
• Wide Area Network (WAN) covers large geographic spans and countries

Network Topologies

• Network Topology is the layout arrangement of nodes like computers, or devices in a computer network. Different topologies can affect a network’s performance, stability and cost.
• Bus Topology uses a main cable for all node connections along a linear design
• Star Topology makes each node connect to a central hub or switch using separate cables
• Ring Topology links all nodes in a circular route with data traveling one way
• Tree topology combines aspects of different structures in a hierarchical layout connecting all computers with each other
• Mesh topology directly connects each node to every other node for redundancy and speed

Advantages of Various Network Topologies

• Bus: The cable may be cut to affect just one node
• Star: easy to diagnose faults and cable failure will not affect the entire network
• Ring: Less cabling is needed, and data transfer speed will be very high
• Tree: expandable and offers simple detection for errors
• Mesh: single point of failure will not break network; Provides high privacy and security

Disadvantages of Various Network Topologies

• Bus: The main cable may break down the network. Single node is the only thing able to transit data.
• Star: Needs large more cables and central unit. If the central unit fails, the entire network fails.
• Ring: A break in the network or one node will close down the network; Expanding is difficult.
• Tree: Maintenance is difficult and configuring tree topology networks is difficult
• Mesh: The cable length is expensive and the structure is complex

Network Protocols

• Network protocols are the communication rules between network devices. Some examples include TCP, IP, UDP, FTP, HTTP, and HTTPS

Network Devices

• A modem converts analog to digital signals and vice versa, performing modulation/demodulation
• A hub connects devices in a LAN, with data sent to every computer
• A switch also connects devices in a LAN but sends data only to the destination computer
• A router facilitates communication between two computers on different networks
• A repeater amplifies signals before retransmission
• MAC address is the 12-digit physical hardware number identifying a network device (6 byte)
• IP address is the numerical address assigned to each device and can be IPv4(32 bit) or IPv6(128 bit)

Unit 3: Python Programming

Introduction to Python

• Python is a high-level, general-purpose programming language designed by Guido van Rossum, Python Software Foundation
• Python is a High level language
• Pyhton is a free and open language

Features of Python

• Flexible programs use high-level language
• Python is free and open source
• Interpreted language execution is what python offers
• Code has case sensitivity
• Platform Independent

Tokens:

• These are individual code snippets within a Python program, which make up statements and instructions and are composed of keywords, identifiers, literals, operators, and punctuators

Naming Identifiers:

• Identifiers must start with a letter or underscore and cannot use keywords, special symbols, or whitespace
• Examples of valid identifiers include A1, Abc, and First_number, while invalid identifiers include 3B, b-m, and a@1

Variable in Python

• Refers to an object or memory location that can store an item or element and are implicitly declared

Comments

• Added using hash sign and provide remark but are non-exeuting and can add multiple quotation for multiple line comments.

Data Types in Python

• Includes integer, numeric, complex number, float, set booloean etc. Literal refers to a value directly represented with fixed data type such as String, etc.

Python Strings

• A group of string of characters which use string values in single quatation or doubles ''

String Slicing

• Can be done, in colon and slicing format as indexes for character display

Operations

• Arithmetic operators (+, -, *, /) perform calculations between two numerical values
• Assignment signs assign to variables
• Operators use for comparison purposes
• Operators assess the relationship of data etc with Logical Operators
• Bitwise Operators the operands' values are processed at the bit level for every two operands.

Punctuators

• Symbols which organize python's language

Type Conversions

• Function in Python is essential to data type conversion

Python Loops

• For loops through and repeats; while repeats

Statements:

• "Jump" to specific location with break, can continue and pass.

String Functions:

• Returns characters in multiple ways such as upper case functions, etc.

Unit 4: Data Structures

Data Structures

• Data is organized, stored, and manipulated, reducing space

Data structures Classifications

• Classified in primitive and non-primitive

Data Structure Details

• Classified in linear and non linear lists

Details in Array

• Stored in one single dimension

Python Stack

• Data structure that is lineal in the last in first out (LIFO) manner

Python Tree

• Made up of non linear data, storing each code in nodes and child elements