Computer Basics and Generations

• A computer is an electronic device programmed to perform tasks, equipped with input/output devices, a CPU, and storage.
• A computer operates by accepting data, processing it into information, and storing results.

Generations of Computers

• The evolution of computers occurred in five generations due to developments in the semiconductor industry.
• First-generation computers (1946-1954) used hundreds of vacuum tubes resulting in large sizes.
• ENIAC, developed in 1946, was an example, measuring 18x80 feet and weighing 30 tons.
• These computers had slow processing speeds, generated lots of heat, were expensive, and required air-conditioned rooms.
• Second-generation computers (1954-1962) used transistors, which were smaller and more reliable than vacuum tubes.
• Second-generation computers were smaller, faster, less expensive, generated less heat, and had features like disk storage and operating systems.
• Third-generation computers (1963-1972) replaced transistors with integrated circuits (ICs), containing multiple transistors.
• The first ICs used small-scale integration (SSI) circuits, with about 10 devices per circuit.
• Third-generation computers were cheaper, smaller, faster, and generated less heat.
• Fourth-generation computers (1972-1984) used Very Large Integrated Circuits (VLICs).
• VLICs (100,000 devices per chip) made it possible to fit millions of components.
• Fourth-generation computers were cheaper, smaller, faster and produced less heat.
• Fifth-generation computing devices use artificial intelligence and are still in development, with applications like voice recognition.
• Parallel processing and superconductors enable AI. Quantum computation, molecular tech, and nanotechnology will drastically affect computers.
• The goal of fifth-generation computing is to create devices with self-organization ability that respond to natural language input.

Classification of Computers

• Computers are classified in three ways
• Classification by Data Representation
• Classification by Purpose
• Classification by processing speed and storage capacity
• Data representation classification includes digital (discrete form), analogue (variable voltages), and hybrid (continuous and discrete) types.
• Purpose classification includes special purpose (designed for a specific task) and general purpose (multi-use) computers.

Classification by processing speed and storage

• Computers are grouped as:
  • Microcomputers
  • Minicomputers
  • Mainframes
  • Supercomputers

Components of a Computer

• A computer's hardware components:
  • Input device: Enters data and instructions.
  • Output device: Conveys information.
  • System unit: Contains processing components.
  • Storage device: Records and retrieves items.
  • Communications device: Sends and receives data.
• Input/Output (I/O) devices translate data into binary digits (0s and 1s) for computer understanding.
• I/O devices can also translate binary digits into human-understandable characters.
• Input devices include keyboards, pointing devices, scanners, digital cameras, and audio/video input devices.
• The keyboard is the common one
• Keyboards convert characters into electrical signals for processing.
• Data-entry devices not requiring keyboards: scanners, voice recognition, audio, and video input.
• Output is data that has been processed into a useful form.
• Output devices convey information, such as display devices, printers, speakers, and data projectors.
• Storage devices store data and are secondary storage.
• Storage devices range from diskettes to video servers.
• A storage device consists of a storage medium and a device to read/write the medium
• Technology of media either magnetic, optical, or magneto-optical.
• Access types are sequential and direct.
• Cassettes use sequential access
• CDs use direct access.
• Tape storage uses sequential access and magnetic storage
• Disk devices use direct access and magnetic, optical or magneto-optical storage.
• Magnetic tapes are secondary storage
• Magnetic tapes store using a magnetic method with sequential access.
• Magnetic tape is thin plastic w magnetic coating
• Divided into columns and tracks, cells are magnetized or unmagnetized (1/0).
• Disk storage devices are named for their storage medium shape.
• Disks are round platters with data on concentric tracks.
• The disk drive rotates the disk and moves the read-write head.
• Disk storage devices use magnetic, optical, or magneto-optical methods.
• Data is stored as electromagnetic charges on the metal oxide film.
• The disk drive read-write head can change the electromagnetic charges.
• Storage capacity is measured in kilobytes (KB), megabytes (MB), and gigabytes (GB).
• Magnetic disks store few MB to several GB (billions of characters).
• Hard disks, compact disks and hard cards are variations of magnetic disks.

System Unit Components

• The system unit houses electronic components to process data, including drive bays, power supply, sound/video cards, processor, and memory.
• Motherboard: main circuit board containing chip with circuits
• CPU, or the processor, executes the functions of a computer
• Containing a control unit and an arithmetic logic unit (ALU)
• The control unit directs operation
• The ALU performs operations
• Processors execute instructions that comprise a machine cycle.
• Most computers use pipelining.
• Processors sometimes use too much energy creating heat.
• Additional cooling technology (Cooling Sinks) needed
• Parallel processing uses processing power of multiple processors simultaneously
• Memory: stores instructions, data, and results.

Memory Items

• Operating system and software
• Application programs
• Stored data
• Each memory location has an address.
• Memory is measured in kilobytes (KB), megabytes (MB), gigabytes (GB), or terabytes (TB).
• Two types of memory: volatile (loses when power is turned off; RAM), nonvolatile (retains when powered off; ROM, flash memory, CMOS).
• Three types of Ram; Dynamic (DRAM), Static (SRAM) & Magneto Resistive (MRAM)
• ROM chips store permanent data and instructions.
• Flash memory is erasable electronically.
• CMOS tech (semiconductor memory) provides high speed with low power consumption
• Access time measures processor's reading and is measured in nanoseconds.
• An expansion slot on the motherboard holds cards enhancing components or providing peripheral connections and video/sound card.
• With "Plug and Play," computers configure adapter cards and peripherals upon installation and connection
• Removable memory includes cards, USB Drives, and PCI Express Cards.
• A port connects a peripheral to a system unit, with connectors joining cables to ports.
• Ports are on notebook on the back, front, and sides
• USB port can connect up to 127 peripherals
• Bluetooth USB adapter converts a USB port to bluetooth
• A bus within a system allows devices inside the systems to freely communicate and translate data
• Data, Address and Control Buses
• Word Size allows processor to interpret
• A bay is opening for adding drives
• Power supply converts wall outlet AC to DC power.
• Some peripherals use an external adapter power supply.
• Software is step-by-step instructions for computer to complete a task or solve a problem.
• Two Categories: Systems and Apps

System Software

• Two types: OS and utilities
• An OS is a set of programmed functions that work to coordinate among hardware components
• A utility runs functions
• Application software makes users efficient
• Business Applications
• Graphics and Multimedia
• Personal and Educational
• Communications
• Application software can be generic or customized.
• Customized or bespoke is designed for the specific entity that determine use.
• Generic: software designed for general purpose that's developed by a dev.