Introduction to Computer Systems

Introduction to Computer Systems

• A computer is a programmable electronic device that processes data based on instructions provided by the user or a program.
• Computers can range from simple calculators to complex desktops or laptops.
• A calculator, for example, takes input (two numbers), processes it (addition), and produces output (the sum).

Computer System

• A computer system comprises devices and programs that work together to process data.
• The main goal is processing raw data (facts, figures) into usable information.
• This process happens in three stages: input, processing, and output.

What Computers Do

• Computer systems typically consist of input devices, a processor (CPU), and output devices.
• Input devices receive data.
• The processor (CPU) processes the information.
• Output devices present the processed information to the user (in various formats).

The Computer System's Components

• A computer system requires both hardware and software to function.
• Hardware refers to the physical components.
• Software is a set of instructions directing the hardware.

Computer Hardware

• Hardware can be classified into groups: input, processing, output, and storage.

Input Hardware

• Input is any data or instruction entered into a computer system.
• Input devices facilitate data entry.
• Examples include: keyboard, mouse, microphone, scanner, barcode reader, digital camera, joystick, trackball, stylus, touch screen/digitizer, and touch pad.
• Input devices are categorized into key input, point and draw, and source data automation.

Key Input Devices

• Key input devices use keys to enter data.
• The keyboard is the only key input device, allowing users to enter alphanumeric characters and commands.

Point and Draw Devices

• Point and draw devices allow pointing, selection, and drawing.
• Examples include mouse, touch screen/digitizer, joystick, trackball, touch pad, and stylus.

Source Data Automation Devices

• Source data automation devices automatically input data without user intervention.
• Examples include scanner, barcode reader, microphone, digital camera, magnetic ink character reader (MICR), magnetic stripe reader (MSR), optical mark reader (OMR), and optical character reader (OCR)

Processing Hardware

• The Central Processing Unit (CPU) is the brain of the computer.
• It processes data by taking raw data and transforming it into information.
• CPUs handle calculations and coordinate all activities within the computer.
• The CPU is made up of smaller units: Control Unit, Arithmetic and Logic Unit (ALU), and Registers.

Data vs. Information

• DATA is raw facts and figures.
• INFORMATION is processed data with meaning and context.
• Data becomes information when provided with context.

Central Processing Unit (CPU)

• Processing speed is measured in MHz or GHz (higher numbers indicate faster processing).
• The CPU contains smaller units: Control Unit, Arithmetic Logic Unit, and Registers.

Output Hardware

• Output hardware presents the processed information to the user, in various forms.
• Output can be categorized as text, graphics, audio, and video.

Categories of Output

• Hard copy output is permanent (e.g., printed documents).
• Soft copy output is temporary (e.g., displayed on a monitor).
• Examples of hard copy devices include printers (impact and non-impact).
• Examples of soft copy devices include monitor, speakers/headphones, projector.

Hard Copy Output Devices

• Printers are the most common hard copy output devices.
• Printers are categorized as impact or non-impact.
• Impact printers create output by physically striking paper. Examples: Line printers, Dot Matrix printers, and Daisy wheel printers.
• Non-impact printers use methods like heat, ink, or laser to create output.Examples: Laser printers, Inkjet printers, and Thermal printers.
• Plotters are specialized printers used for large-scale drawings, like blueprints.

Soft Copy Output Devices

• Monitors display information on screens (Cathode Ray Tube (CRT) or Liquid Crystal Display (LCD)).
• Projectors display information onto a larger surface for viewing.
• Speakers and headphones generate output sounds.

Storage Hardware

• Storage hardware stores data (instructions and information) for immediate or later use.
• Storage can be categorized as Primary storage and Secondary storage.

Primary Storage (Memory)

• Primary storage holds data currently being used by the computer. It's volatile.
• Examples include RAM (Random Access Memory).
• ROM (Read-Only Memory) is also considered primary storage. Information on ROM is permanent.

Secondary Storage

• Secondary storage holds data for long term storage. It is non-volatile; data is safe when the device is powered off. Examples: Magnetic Storage (floppy disks, hard drives, magnetic tapes), Optical Storage (CDs, DVDs, Blu-ray disks), and Solid-State Storage (USB flash drives, SD cards).

Comparison of Primary and Secondary Storage

• Primary storage is expensive but has faster access speeds.
• Secondary storage is more affordable, has slower access speeds, but stores data permanently unless manually deleted.