Computer Hardware

Computer Hardware

1. CPU

   • The CPU carries out all the processing in a computer.
   • The Fetch-Execute Cycle. 1.Fetch the instruction from memory. 2.Decode the instruction to find out what processing to do. 3.Execute the instruction.
   • The Boot Sequence is a sequence of processes that contains all the information and instructions to get the computer up and running.
   • The speed of the FEC is determined by an electronic chip. its measured in cycles per second(Hz)
   • Cache Memory has access times similar to the CPU but is very expensive.
   • Multiple Processor Cores use multiple CPUs working together.

2. Memory

   • Vital Memory is part of the hard drive used as an extension to RAM. it is used when the computer does not have enough RAM to hold all the data and programs required.
   • RAM- Random Access Memory. it is volatile, large and contains the operating system.
   • ROM- Read Only Memory. it is non volatile and stores instructions, contains the boot program and is small.
   • Flash memory is a type of ROM that can be rewritten. its used as a portable medium for storing and transferring data.

3. Binary Logic

   • all computers work in binary and use simple logic circuits to make calculations. the three main gates used are:
   • Logic Gates can be combined to make more complex circuits.
   • Computers use binary values because it is easy to tell the state of a switch. on/off or 1/0

4. Input&Output Devices

   • Input Devices.
     • Keyboard used for data entry into a computer.
     • Mouse controls a pointer on screen that can be controlled by clicking buttons.
     • Braille keyboard can be used by people with visual impairments to type text and commands by using keys with embossed patterns that match the standard Braille charcters.
   • Output Devices.
     • Monitor to display text, images and video.
     • Speakers produce sound output such ass music, warning sounds and voice for communication.
     • Printer produces hard copy on paper.

5. Secondary Storage

   • Magnetic Hard Disc stores the operating system, installed programs and user data. they are reliable, high capacity and low cost.
   • Optical Disk is excellent for transferring files or distributing software. they are good capacity, low cost and light&portable.
   • flash memory uses little power and is used in hand held devices, more expensive than hard disk and good capacity.
   • Main Considerations when Selecting Storage. consider capacity, speed, portability, durability and reliability.

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