BUYING A COMPUTERTERM 2 – AIT

HARDWARE COMPONENTS AND FUNCTIONS

• describe the components of a multimedia computer system

• processing (central processing unit)

• input devices e.g. mouse, keyboard

• output devices i.e. monitor, printer

• memory/storage

• primary e.g. RAM, ROM, cache

• secondary i.e. flash, magnetic

• communication devices

PROCESSOR – CENTRAL PROCESSING UNIT

• Interprets and carries out basic instructions that operate a computer.

• The speed of the processor significantly impacts computing power and management of all operations.

• Dual core processors contain two separate processors.

• Quad core processors contain four separate processors.

• Benefit of multicore processing is most noticeable when running multiple applications i.e. anti-virus software, spyware remover, email and media player.

• Multicore processors are more energy efficient and emit less heat.

SPEED OF THE CPU

• The processor relies on a small quartz crystal circuit to control the timing of all computer operations. The system clock generates regular electrical pulses each pulse is a tick or clock cycle. In the past processors used a clock cycle to execute each instruction.

• Processors today use superscalar technology which means they can execute more than one instruction per cycle or tick.

• Current speeds are in the Gigahertz range.

• Giga = billions 1,000,000,000

• Hertz is one cycle per second

• 3.0 Ghz = 3 billion clock cycles per second

• The faster the clock speed the more instructions the processor can execute.

INPUT DEVICES – MOUSE AND KEYBOARDS

• Input device is any hardware component that allows users to enter data and instructions (programs, commands and user responses) into a computer.

• Mouse – user controlled pointing device that is used to select buttons, icons, menus, links and text on a monitor.

• Keyboard – input device that contains keys users press to enter data and instructions into a computer. Most have numeric, alphabet and other special character keys.

OUTPUT DEVICES – MONITOR

• An output device is any type of hardware component that conveys information to the user.

• Monitor – display device that visually conveys text, graphics and video information to the user. Typically called a soft copy.

• Some monitors use Liquid Crystal Display (LCD) technology to display an image. Liquid compound is used typically they also contain fluorescent tubes that emit light waves towards the liquid crystal cells. Quality depends on the resolution and this is measured in the number of horizontal and vertical pixels in a display. So a monitor that has a 1440 X 900 resolution has a total of 1,296,000 pixels to create a screen.

• Others monitors use Light Emmitting Diodes (LED) technology instead of fluorescent tubes LED LCD monitors use white LEDs for the backlight, which allows for a slimmer profile, longer life, and less power consumption.

OUTPUT DEVICES –PRINTER

• An output device that produces text and graphics on a physical medium such as paper, transparency or other polymer. Often called a hard copy.

• Most modern printers are non-impact printers which use spray ink, heat or pressure to create the print document.

• Printer resolution is measured by the number of dots per inch (dpi), a dot is a drop of ink the smaller the drops per inch the higher the resolution.

• The speed of a printer is measured by pages per minute (ppm).

• Two common printers are inkjet and laser printers. Typically laser printers print at a faster rate and have better overall quality than inkjet printers.

MEMORY/STORAGE

• Memory consists of electronic components that store instructions waiting to be executed by the processor, data needed by those instructions and the results of processed data. Memory usually consists of one or more chips on the motherboard or some other circuit board in the computer.

• Memory can store;

1) The operating system and other system software that controls and maintains the computer system

2) Application programs that carry our specific tasks such as word processing

3) The data being processed by the application programs and resulting information

RANDOM ACCESS MEMORY (RAM)

• RAM also called main or primary memory consists of memory chips that can be read from and written to by the processor and other devices.

• As programs and data are requested they load into the RAM from storage. The processor interprets and executes a program’s instructions while the program is in RAM.

• RAM can accommodate multiple programs simultaneously.

• Most RAM is volatile, no power = no save.

• SDRAM = Synchronous Dynamic RAM re-energiezed constantly, faster than regular RAM and synchronised to the system clock for faster processing.

• DDR SDRAM = Double Data Rate chips are faster than SDRAM because they transfer data twice for each clock cycle. DDR2 and DDR3 are faster still.

• Dual channel is faster than single channel as it delivers twice the amount of data to the processor.

READ ONLY MEMORY - ROM

• Refers to memory chips storing permanent data and instructions.

• Most can not be modified.

• Firmware - permanent software programmed into a read-only memory.

• It is non-volatile which means it can not be lost when the power is turned off.

• Many devices have ROM chips which are programmed when they are manufactured i.e. a printer may have a ROM chip which stores fonts.

CACHE• Memory cache helps speed the processes of the computer

because it stores frequently used instructions and data. When the processor needs an instruction or data it searches memory in this order;

1) L1 cache built directly into the processor, very small capacity.

2) L2 cache usually built directly on the processor, slower than L1 but larger capacity.

3) L3 cache on the motherboard separate from the chip.

4) Then the RAM and other much slower storage medium.

MEMORY SIZE

• A byte (character) is the basic unit in memory. Each byte resides temporarily in a location in memory that has an address.

• Manufacturers state the size of memory chips and storage devices in terms of the number of bytes the chip or device has available.

Term Abv Approx Bytes Exact Bytes Approx Pages

Kilobyte KB 1,000 1,024 ½

Megabyte MB 1,ooo,ooo 1,048,576 500

Gigabyte GB 1,000,000,000 1,073,741,824 500,000

Terabyte TB 1,000,000,000,000 1,099,511,627,776 500,000,000

STORAGE

• Storage holds data, instructions and information for future use. Every computer stores system software and applications software. To start up, a computer locates an operating system in storage (usually a hard disk) and loads it into memory (RAM).

• In addition to system software and applications users store a variety of data on various storage devices.

• Some characteristics of hard disks include capacity, platters, read/write heads, cylinders, sectors, tracks, revolutions per min, transfer rates and access time.

• The larger capacity hard drives are in Terabytes.

• Redundant Array of Independent Disks (RAID) configuration that connects smaller disks into a single unit that acts as a large hard drive.

DESIGN AND ACQUISITION OF HARDWARE AND SOFTWARE

• Explain the following factors when purchasing/acquiring hardware/software solutions to suit a media rich environment:

• functions of hardware and software—does the hardware and software meet your requirements?

• fundamental technical capabilities of hardware and software—can the hardware meet the minimum requirements of the software?

• output quality—does the software give the desired output?

• cost of hardware and software—is the cost within budget?

• ease of use of software and hardware—who will use the software/hardware? What skills will they need to learn?