Computer Components and Hardware

Computer Components

• A computer is an electronic device that operates using software (instructions) stored in memory. It takes input data, manipulates it, and produces output information.

Hardware

• Hardware refers to the physical components of a computer system, including the personal computer (PC).

• Key hardware categories:

  • Central Processing Unit (CPU): The control unit fetches and decodes instructions, while the Arithmetic Logic Unit (ALU) performs calculations.
  • Main Memory (RAM): This volatile memory holds instructions and data while the program is running.
  • Secondary Storage Devices: Non-volatile storage like hard drives, CDs, DVDs, and flash drives.
  • Input Devices: Send information to the computer, including keyboards, mice, digital cameras, and microphones.
  • Output Devices: Send information from the computer to the outside, including monitors, printers, speakers, and headphones.

• Examples of output devices include inkjet and laser printers. Inkjet printers are affordable and produce high-quality color prints quickly. However, laser printers are faster, produce higher-quality output, and are more expensive.

CPU's Role

• The Central Processing Unit (CPU) cycles through three steps to run a program:
  • Fetch: retrieves the next instruction from memory.
  • Decode: interprets the instruction and creates a signal.
  • Execute: sends the signal to the appropriate component to perform the operation.

Main Memory

• Main memory (RAM) holds instructions and data for the CPU.
• Volatile memory, meaning the content is lost when the computer powers off.
• Also referred to as random access memory (RAM).

Main Memory Organization

• Bit: The smallest piece of memory. It has two values (0 or 1).
• Byte: 8 consecutive bits.
• Word: Usually 4 consecutive bytes (with an address).
• Computers use binary language (0s and 1s). A unique combination of 8 bits defines a character or symbol.

Secondary Storage

• Non-volatile storage - data remains even when the computer is turned off. This includes hard drives, CDs, DVDs and flash drives.

Input Devices

• Used to send information to the computer, examples: keyboard, mouse, digital cameras, disk drives, CD/DVD drives, microphones, and scanners.

Output Devices

• Used to send information from the computer to the outside, examples: monitors, printers, speakers, headphones, projectors, GPS systems, and CD/DVD recorders, and USB flash drives.

Computer Speed

• Measured in megahertz (MHz) or gigahertz (GHz).
• The clock speed indicates how quickly computations are performed in RAM. A faster clock speed generally indicates faster processing.

Computer Speed (categories)

• Mainframe: supports many simultaneous users and programs.
• Supercomputer: designed to perform complex calculations rapidly.
• Embedded: Self-contained and specially designed for a specific function (e.g. thermostat).
• Personal computers: general-purpose for single users.
• Smartphone: versatile devices with numerous applications, cameras and web connectivity.

Software

• Instructions that enable a computer to execute tasks.
• Divided into operating system software and application software.
  • Operating system software: manages computer hardware and programs, enabling multitasking and single-user or multi-user operation (e.g., MS-DOS, UNIX, Windows).
  • Application software: enables specific tasks like writing letters, browsing the Internet, or drawing pictures, depending on the operating system's instructions (e.g., word processors, web browsers or video games.)
  • Programs are a set of instructions that direct computers to perform tasks.
  • Programs are written using programming languages.