COMPUTING HARDWARE

COMPUTING HARDWARE

1. CPU

   • Arithemtic Logic Unit
     • Carries out calculations as well as similar numeric functions, such as comparing two numbers to see which is larger
   • Control Unit
     • Responible for retrieving data/instructions from the correct location in memory and executing those instrcutions. This might include calling the ALU if the result of a calculation is needed
   • CLOCK SPEED
     • Is measured in Hertz (Hz). One Hz means one operation per second, one MGHz means 1 million operations per second & GHz means one billion operations per second.
   • Size of Cache
     • Cache memory is high-speed memory that stores frequently needed instructions/data. The larger the cache, the more it can store and the faster the CPU appears to work.
   • Number of Cores
     • a dual-core or quad-core processor is not going to operate two or four times faster than a single core processor however, more cores usually mean a faster CPU

2. LOGIC GATES

3. Memory

   • RAM RANDOM ACCESS MEMORY
     • Volatile memory which when a computer is turned off the content of RAM is lost. When a program is loaded from a computers hard dick, its data/instructions are loaded into RAM. If a computer has more RAM it will be able to run more applications at the same time.
   • ROM READ ONLY MEMORY
     • RO means that the content cannot be edited or erased. ROM stores data/instructions that will not need to be updated. ROM will typically store bootstrapping instructions which tell the computer where to find the initial steps in findng and installing the operating system when the computer is turned on.
   • VIRTUAL MEMORY
     • If RAM is not large enough to store all of the data and instructions that is required, virtual memory may be used. This is when part of the hard disk is used as an extension of RAM and temporarily given memory addresses as if it wereRAM
   • Cache Memory
     • Stores copies of data/instructions from RAM that are accessed regularly.
   • Flash Memory
     • It is non-volatile (continues to store data without electricity source) . It is portable Solid-state memory for example USB and Memory Cards/Drives.
       • USB DRIVES - frequently used to transfer data between systems. MEMORY CARDS - can also be used to transfer data however, they are more commonly used in devices such as digital cameras/tablets

4. USERS WITH SPECIAL NEEDS

   • OUTPUT
     • Braille Printer - Using the braille system to print out data/files with punctured holes that can be read by blind people.
     • Text-to-speech - A combination of speech software/speakers to read documents/web pages to visually impaired people
     • Screen Magnifiers - These devices are aimed to help partially-sighted users, clip into the front of a monitor to enlarge the visible display for them to be able to read.
   • INPUT
     • Eye-Typer - allows the user to communicate using their eyes. The computer moves the cursor by the movement of their eye.
     • Braille Keyboard - To allow visually impaired users to type data/instructions into the computer
     • Puff Suck Switch - Allows users to input instructions by sucking or blowing onto a tube. Good for mobility users to answer boolean questions

5. SECONDARY STORAGE

   • SOLID STATE
     • CAPACITY = range from 1GB-64GB SPEED = Transmits data at a rate of 5 Million bits per second PORTABILITY = Very small&light - designed to to be moved from computers to other comp DURABILITY = Very sturdy
       • Commonly used by students to access their work on different computers
   • OPTICIAL
     • CAPACITY = CD - 700MB DVDS - 5GB Blu-ray disks - 25GB SPEED = Blu ray disks are more quicker than CD&DVD PORTABILITY = small and light DURABILITY = Sturdy although if becomes stratched it will not work
       • Useful to use as most computers have optical drives
   • MAGNETIC
     • CAPACITY = Variable however new computers have them measured in terabytes SPEED = far quicker than any external device PORTABILITY = difficult & time consuming DURABILITY = Very well protected in computer and protected in metal case when removed
       • Most programs are stored of hard disk drive

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