Chapter 2 Hardware

Chapter 2 Hardware

1. Processor Technology

   • Microprocessors: At the centre of a computer is a processor, it is responsible for performing all instructions and tasks. They are loaded from secondary storage into RAM and then the processor executes each of these instructions on by one. The speed of the processor determines how quickly tasks can be completed.
   • Clock speed: The speed at which a processor executes instructions is called the clock speed and is measured in Megahertz MHz or Gigahertz GHz. The higher the clock speed the more instructions a processor can perform in a given period of time.
   • MIPS: Millions of Instructions Per Second is another measure of processor performance. MIPS figures should be used with caution because it is possible to quote misleading figures based on instructions which execute the quickest, rather than those that represent real life computing tasks.
   • Motherboards: The processor connects directly to the computers motherboard which in turn provides ports and connections for all other parts of the system. It also has slots for the RAM, connectors for hard disks, slots for attaching expansion cards like video cards or sound cards, connectors for the mouse and keyboard.
   • Multicore Processors: Increased processor performance can be achieved by adding additional processor cores. Each core is capable of running an individual program thread at once, boosting performance.

2. Input Devices

   • Radio frequency Identification: Is a technology which some people believe will replace barcodes. Consists of two components- RFID tag which is attached to the surface of an item and an RFID reader to query the tag and retrieve its information.
   • Radio tags: used for locating or tracking objects.
   • Webcams: A low resolution video camera.
   • Digital Cameras: Useful way of inputting image, video, and sound straight into a computer, can be done using a USB or Firewire connection.
   • Sensors and Probes: Sensors are used for measuring some aspect of the physical world, such as humidity, temperature, light or pH.
   • Magnetic Ink Character Recognition: Is a specialised technology that uses ink containing iron particles, making it magnetic Written in a special font making it human readable.
   • Scanners: A scanner is a device for digitising a piece of paper. A digital image of paper being scanned is stored as a standard image file. Happens even if it contains text.
   • Game controllers: Joysticks and game pads are both used by games players.
   • Smart cards: Are plastic credit card style cards that differ from normal magnetic stripe cards by having a higher storage capacity and an embedded processor.
   • Magnetic Stripe Readers: Bank cards, credit cards, hotel key cards and some frequent traveller cards feature a magnetic stripe on the reverse side. They store a small amount of data which is read using a magnetic stripe reader.
   • Optical Mark Recognition: Input method for speedily reading and counting multiple choice style answer papers.
   • Barcode Scanners: Uses a laser to shine light onto a barcode label. The thickness of the lines and the spacing between the lines on the barcode determine the amount of reflected light.
   • Microphones: Allows sound data to be input into the computer. Many laptops have microphones built in.
   • Touch Screens: Allow users to interact with computers using their hand or a specifically designed pen.
   • Trackballs: A relatively large ball which is fixed in place so that the user can spin it around, controlling a pointer on the screen. One advantage is that they don't move across the desk.
   • Touch pads: Common input device when theres not enough space for a mouse.
   • Mice: Standard point device on most desktop computers. Has two buttons and a scroll wheel to perform tasks like scrolling through documents or web pages.
   • Soft Keyboards: A keyboard that is represented by a series of buttons drawn on a monitor or screen. User selects options using a pointing device like a mouse or a touch screen.
   • Concept Keyboards: each key is programmed to perform custom functions. Usually in restaurants to enter the items a customer has purchased.
   • Keyboards: QWERTY is most common. Dvorak are used and claimed to increase typing speed by rearranging commonly paired letters. Multimedia keyboards are QWERTY but with hot keys for opening common applications e.g. web browsers and music.

3. Types of computers

   • Super computers: Largest, fastest, most powerful and most expensive. Achieve high processing speeds.
   • Mainframes: Very powerful computer and are optimised for high data throughput. Can read large amounts of data.
   • Desktop computers: Common in homes, offices and schools because they are cheap compared to laptop computers.
   • Laptop computers: Designed for simple internet access and word processing.
   • Netbooks: Are laptop computers with lower specifications than normal, designed for maximum portability.
   • Smart phones: include built in camera to record video sound and images, access to apps, texts and phone calls.
   • Personal Digital Assistant: Bigger than a phone smaller than a netbook best suited for quick viewing and input of information.
   • Embedded systems: Is a specialised computer which is hidden inside another device. They are found in cars where they control anti lock braking and engine management systems.

4. Output Devices

   • Screens: CRT(cathode Ray tube) displays are the big, deep, monitors that are used to be used on almost all desktop computers. LCD (Liquid Crystal Displays) are generally cheaper, thinner, lighter and produce higher quality images than CRT displays. They have a native resolution which refers to the fixed number of dots that make up the screen.
   • Printers: Printers produce hard copies of documents and files. Vary in how they produce an image. Inkjet printers work by squirting ink onto a page through a series of nozzles. The quality is measured by dots per inch DPI. Laser printers produce higher quality printouts than inkjet printers but are expensive.
   • Speakers: Speakers can be simple ear phones to complex multi- speaker arrangements. Used for entertainment.
   • Are any items of hardware that the computer uses to present data to the user. Like input devices output devices can output text, images, videos, sound or other types of data.

5. Storage Devices : Are used to store both data that a computer system processes and the software programs that tell it how to process that data.

   • Primary Storage: Refers to the high speed electronic memory found inside a computer. Primary storage is the only storage that the processor can access directly because it is connected directly to the bus on the motherboard.
   • Random Access Memory RAM: Is a temporary storage area for programs and data that are being used in a given moment. When a program or piece of data is first needed, it is loaded from secondary storage into RAM. The processor then fetches the instructions and data from RAM and saves the results back into RAM.
   • Read Only Memory ROM: Is a type of primary storage whose contents cannot be changed. Because of this the contents of ROM are programmed at the time of manufacture.
   • Secondary Storage: Used to store all of the data and programs installed on a computer system- even if they are not currently being used.
   • Magnetic Tapes: Have been used in computing for many years. Use magnetic audio tapes to store all their software and data.
   • Magnetic Disks: Most common type of secondary storage found in computers today. Consist of a series of disk platters spinning at up to 10000 rpm inside a solid case. A read/write head moves backwards and forwards over the disk and magnetically charges areas of it to storage data.
   • Optical Storage: Optical disks are like CDS, DVDS and Blu-ray disks read and storage data using lasers. Small lands and pits in the disk surface reflect laser light in different ways- the difference between these is interpreted as either a binary 1 or a 0 by the computer.
   • Flash memory: Is a technology that stores data using electronic logic dates. Have no moving parts giving them three main benefits over hard disks- Less susceptible to damage from drops and knocks, less power than hard disks, offer much faster access than hard disks.

6. Ports and Connectors: Various ports and connectors are used to connect input, output, storage and networking devices.

   • VGA: Used for connecting a standard monitor, either CRT or LCD, to a computer or games console.
   • DVI: Digital Video Interface an the newer high definition multimedia interface are used to connector or digital displays to digital video sources.
   • SATA and eSATA: A high speed standard for connecting hard disks, DVD and Blu-ray players.
   • IDE: An older standard for connecting hard disks. Although slower, IDE is still widely used for devices like CD and DVD drives.
   • USB: (Universal Serial Bus) A modern standard used for connect a wide variety of peripherals including mice, keyboards, external hard disks, digital cameras, printers, scanners and flash drives.
   • FireWire: A high-speed interface used for different peripherals including digital video cameras and external hard disks. FireWire is less common than USB connections, but offers a much higher transfer rate.
   • Ethernet: A standard for wire Internet access, available on virtually all computers.
   • PS2: An older standard for connecting mice and keyboards. Generally superseded by USB.

7. Storing data: Bits and Bytes: Your computer is representing all of its data internally as binary digits- ones and zeroes. These are known as bits, on their own they are not very useful because they only represent on of two state- on or off, yes or no, one or zero. Eight bits are grouped together into a unit called Bytes. Bytes are grouped into increasingly larger units called kilobytes, megabytes, gigabytes and terabytes.

   • ASCII: (American Standard Code for Information Interchange) A standard coding scheme for representing text using the english alphabet. Using ASCII each byte of data represents a single character.
   • Unicode: More modern coding scheme which aims to solve some of the problems of ASCII. Unicode uses up to 4 bytes to represent each character, allowing many thousands of characters to be represented, they include non english alphabets and right to left languages.
   • Plain text: ASCII and Unicode are examples of plain text. They specify the characters that make up a text but they do not include ways to specify other formatting attributes such as the font type, size, features like bold or underline, or coloured text.
   • Graphic standards: Computer graphics are represented as bits and bytes just like all other computer data. Different file formats such as BMP, JPEG and PNG store the image data in different ways, but in general all true colour images use a similar scheme.