Introduction to Computers

• The term "computer" comes from the word "compute" meaning to calculate.
• A computer is an electronic machine that performs calculations and controls operations expressed in logical or numerical terms.
• It's an electronic device performing mathematical and non-mathematical operations using instructions to process data.

Characteristics of Computers

• Computers were developed to perform complex tasks like calculations and data processing.
• They are integral to modern life, found in offices, homes, appliances, and infrastructure.
• Computers process data very quickly, measured in millions or billions of instructions per second (MHz).
• Computers are accurate, with the level of accuracy depending on instructions and machine type.
• Faulty instructions or incorrect input lead to faulty results, known as "GIGO" (garbage in, garbage out).
• Reliability is measured against a standard for operation without failure.
• Computers have built-in problem-solving capabilities for continuous monitoring without human intervention.
• Computers can perform multiple tasks simultaneously.
• A computer can only execute programmed instructions.
• They need specific instructions for any operation and can't derive conclusions without intermediate steps.

Evolution of Computers

• The evolution is defined by generations of computers.
• Each generation features new technological developments, creating more powerful, efficient, and smaller computers.
• There are currently five generations of computers.
• First Generation: Vacuum Tubes (1940-1956)
• Second Generation: Transistors (1956-1963)
• Third Generation: Integrated Circuit (1964-1971)
• Fourth Generation: Microprocessor (1972 – 2010)
• Fifth Generation: Artificial Intelligence (2010 – Present)

Classification of Computers

• Computers vary in size and type, from palm-sized to room-sized.
• Some are for single users, while others handle multiple users simultaneously.
• Classifications are based on purpose, data handling, and functionality

Classification by Purpose

• Computers can be for general or specific purposes.
• General-purpose computers handle a range of tasks and store numerous programs, schools and homes usually use these.
• Specific-purpose computers are designed for particular problems with instructions built-in, lacking versatility, airline reservations and air traffic control use these.

Classification by Data-Handling Techniques

• Computers are classified into Analog, Digital, and Hybrid based on data processing.

Classification by Functionality

• The four major categories based on physical size, performance, and application areas are: Micro, Mini, Mainframe, and Super Computers.
• Microcomputers are small, low-cost digital computers with a microprocessor, storage, input, and output channels.
• Microcomputers include desktops, laptops, and handheld devices like PDAs.
• Desktop computers are made of separate components and are for use on a desk or table.
  • Spare parts are standardized and cheap.
  • They have faster processors for the same price as laptops.
  • There are fewer overheating issues.
  • They lack portability and have heavy, wired components and use portable disks.
• Laptop computers have all components in one portable unit.
  • Portability is an advantage.
  • People can work anywhere, especially with Wi-Fi.
  • Loss and theft are disadvantages.
  • Battery life is limited.
  • Laptops have less flexible keyboards and pointing devices.
  • Laptops are more compact, so overheating can be a problem.
• Hand-held computers such as PDAs are portable and can fit in a pocket.
  • PDA users use stylus instead of keyboard.

The Computer System

• It is a system of components working together to convert data into information.
• Processing is electronic with minimal user intervention.
• Computers are not "intelligent thinking machines."
• Computers need instructions, called programs, to be useful.
• Physical parts (CPU, input, output, storage) are hardware.
• Hardware connected outside the CPU is a peripheral (e.g., keyboard, mouse).
• Computer systems have two main components: hardware and software.
• Computer hardware is tangible.
• The CPU or Microprocessor is the computer's "brain".
• Examples of hardware: monitors, keyboards, mice, printers, scanners.
• All-In-One printers have scanner, photocopier and printer functions.
• Other hardware inside the case are: RAM, ROM, processing chips, motherboard, video cards, sound cards, internal hard disk drives.
• Computer Hardware consists of five primary components: input device, output device, storage device, processor, communication devices

Input Device

• It allows data entry to be processed by the computer or give instructions.
• The keyboard is the primary input device.
• Other input devices are mice, scanners, digital cameras, microphones.

Output Device

• Allows us to see information on a monitor or from a printer.
• It displays information/data entered or from the system unit or processed information.
• Output can be in soft or hard copy.
• Soft copy is what you see on the monitor and is temporary.
• Hard copy can be touched and carried and is usually paper.

Storage Device

• Storage devices allow computers to keep data, information, and programs.
• There are two kinds of storage devices: primary and secondary.
• Primary storage is temporary working storage.
• Secondary storage stores data/information permanently on disk

Primary Storage

• There are two forms of primary memory: RAM (Random Access Memory) and ROM (Read Only Memory).
• RAM is a temporary storage area for information being used, erased when the computer turns off.
• ROM is special memory that remembers components attached to the system, information cannot be changed.

Secondary Storage

• It consists of devices storing data/information permanently on disk.
• Disk can store data indefinitely.
• Disks include hard disks, compact disks, and flash disks.
• A disk is plastic or metal with a magnetic coating for storing data.
• A disk drive reads or records on disk.
• The hard disk is metal coated with magnetic properties, located in the desktop system unit.
• Information is read and recorded.
• The hard disk drive uses the letter "C".
• A compact disk (CD)stores music, programs and information, located on the system unit front.
  • It is read by a CD-ROM drive, or a CD writer can write compact disks.
  • Common symbols for CD-Rom are “D” and “E”.
• The flash disk is removable and can carry data and information from one computer to another.
  • They are commonly represented by “E” or "F".

Processor

• The brain of the computer interprets and carries out instructions
• Composed of the CU (Control Unit) and AU (Arithmetic Unit).
• Examples are Intel Pentium and Intel Core Dual.

Communication Device

• It enables sending and receiving data, instructions, and information between computers.
• A telephone or cable modem is a widely used example.
• Communications rely on transmission media like telephone lines, cables, cellular networks, and satellites.
  • Some transmission media are wireless.

Computer Software

• This is the set of programs enabling hardware to perform tasks in order.
• It is the instructions telling the computer what to do.
• Hardware and software must work together.
• Computer software is classified into: system software and application software.

System Software

• It controls or maintains a computer's operations and devices,
• It enables booting, launches applications, transfers files, controls configurations, manages files, and protects from unauthorized use.
• The two types are: operating systems (OS) and utility programs.

Application Software

• Application Software are the programs allowing users to perform specific tasks.
• Common categories: word processing, spreadsheet package, presentation package, database package, accounting package, and painting package.

Word Processing

• These are used to create, edit, format, and print documents.
• They offer easy changes, like correcting spelling, changing margins, and relocating paragraphs. These documents can be printed quickly and accurately and easily stored on a disk for future use.

Spread Sheet Package

• It allows calculations on rows and columns of numbers.
• Spreadsheet information is often converted into charts.

Presentation Package

• Allows the user to create slides for presentations.
• Special projection devices project slides directly from the computer.

Database Package

• This allows entering, retrieving, and updating data efficiently.
• These offer flexible inquiry/reporting features, accessing/creating custom reports.