Output Devices 3

Printer Memory

It is important to realize that most printers have their own memory chips, in the same way that each computer has its own memory. If you are printing very large graphics (i.e. pictures), and want the best quality output from your printer then you should consider adding more memory to your printer. This must only be done by a qualified person, and has the benefit of really speeding up the rate at which you can print pages inmany cases.


Cost of printer peripherals

When you buy a printer, one of the things the salesperson will not necessarily
stress is how much it will cost to keep that printer running. Laser printers do
not use ink; they use something called toner that is normally supplied in a
sealed unit called a toner cartridge. Each toner cartridge will allow you to
print a certain amount of pages and when the toner is used up it needs to be
replaced. In some cases the costs of these toner cartridges is very high.

Plotters

A plotter is an output device similar to a printer, but normally allows you to
print larger images. Their use is common in the design and research sector.

Speakers

Most computers are sold with the capability to add a pair of speakers to your
system unit. In fact, in some cases, the monitor may have speakers built
directly into the unit. This enhances the value of educational and presentation products and can now be considered a standard PC component.

Speech synthesizers

A recent development is the ability not only to display text on a monitor but
also to read the text to you. Thus, you could receive a text email from a
colleague and the system could read that email to you. This is of enormous
benefit to the visually impaired when using a computer. On the flip side, it is
now possible to use a microphone to talk to the computer and for the computer to directly convert the spoken word into text that will be displayed within say your word-processor. While these systems are far from foolproof they are getting better as more advanced software is being made available.

Output Devices 2

Different types of printer

There are many different types of printers. In large organizations, laser
printers are most commonly used because they can print very fast and give a very
high quality output. In most organizations, the printers are connected to the
computers via a network. This means that each person with a computer does not
require his or her own printer. Each computer connected to the network can print
using a particular shared printer.

Laser printers

Laser printers produce high print quality at high speed. They are called "laser printers" due to the fact that they contain a small laser within them. There is a wide range of laser printer manufacturers and one buzzword to be aware of is Postscript, a type of printer that is designed to give very high quality reproduction of pictures.

Color laser printers

Originally, most laser printers would only print in black and white (mono). More recently color laser printers have dropped in price and are entering wide spread use. While many of these produce excellent results, you should be aware of the fact that the "price per page", especially if you are using a lot of color on a page can be very high compared to the cost of printing in black and white.

Inkjet printers

Inkjet printers work by using tiny jets to spray ink onto the paper. Inkjet printers are very quiet in operation and produce print quality comparable to that of laser printers, though laser printers still have the edge in terms of speed. Inkjet printers are ideal for low volume printing where high quality print is required and speed is not a high priority, e.g. printing letters in a small office or in the home.

Dot Matrix printers

Dot matrix printers work by firing a row of pins through an ink ribbon onto the paper. The more pins the print head has the higher the quality of the print, most modern dot matrix printers have 24 pins. Unfortunately, dot matrix printers can generate a lot of noise and do not produce a very high quality of print, especially when printing graphics. As a result, the inkjet printer has now largely replaced the dot matrix printer. Dot matrix printers are used for high volume / low quality printing, e.g. printing company pay slips

Output Devices 1

Identify common outputdevices for displaying the results of processing carried out by a computer, suchas: monitors, screens, printers, plotters, speakers. Know where these devicesare used.

The VDU (computer monitor or screen)

The VDU (Visual Display Unit) is the computer
screen used for outputting information in an understandable format for humans.
Remember that at the end of the day the computer works in binary code (a series
of on/off impulses). It is hard to realize that the original electronic
computers did not have a screen

Flat screen monitors

Traditional computer monitors are based on the same sort of technology that is
used within a television screen.

More recently, flat screen computer monitors have become available. These take
up a lot less room on a desk and use less energy than the traditional, more
bulky monitors.

Screen size

You should be aware that often if you specify a screen of a certain size, say a
17-inch screen, that this is the size measured diagonally, not horizontally
across the screen. If you are upgrading you should also ask for the "visible
viewing area" of the screen.

Graphics for games

Many games require very advanced graphics cards (boards) to be installed within
your computer to make them run. These advanced graphics cards contain their own
CPU that is dedicated purely to displaying the graphics on your screen. You
should find that a recent PC has this advanced graphics capability built-in
where as PCs from only 2-3 years ago may not.

Computer presentation projection devices

These are projection devices that can be attached to your computer and are
useful for displaying presentations to a group of people. They are best used in
combination with presentation programs, such as Microsoft PowerPoint. They are
used within education and are also very popular for sales presentations. The
price of these devices has dropped dramatically recently. When purchasing one of
these devices the two things to look out for are the resolution
(go for a minimum of XGA) and the brightness of the lamp (the brighter the
better). Other factors to be aware of is the quietness (or otherwise of the
device) and well as the cost of replacement bulbs.

Input Devices 2

Joysticks

Many games require a joystick for the proper
playing of the game. There are many different types, the more sophisticated
respond to movement in 3 axis directions, as well as having a number of
configurable buttons. Like most things in life you get what you pay for with
joysticks and it is worth investing in a good, strongly constructed model,
especially bearing in mind that children will hammer these devices whilst
playing games.

Voice input for PCs (microphones)

Early voice recognition systems offered very poor results, due to the
limitations of the software combined with hardware limitations. It takes an
awful lot of CPU processing power to convert the spoken word into text that
appears on the screen. Things are changing rapidly however and recent systems
allow you to talk to a PC and see text appear on the screen. Most of these
systems require an initial training period, where you train the software to
respond to your particular voice. While still not perfect this is a key
technology of the future.

Web Cams

Ever since it was invented, the Web has become increasingly interactive. You can
now use a small digital movie camera (a Web cam) mounted on the PC monitor to
allow two-way communication involving not just text communication but sound and
video communication as well. While not yet considered a standard piece of PC
kit, it is only a matter of time …

Digital Cameras

A digital camera can be used in the same way a traditional camera can, but
instead of storing images on rolls of film which require developing, the images
are stored digitally in memory housed within the camera. These pictures can
easily be transferred to your computer and then manipulated within any graphics
programs that you have installed on your computer. Currently they are limited by
the quality of the image recorded and the number of pictures that you may storewithin the camera.

Input Devices

Identify some of the main devices for inputting data into a computer such as: mouse, keyboard, trackball, scanner and more .

The Mouse
The mouse came into common use on a PC with the introduction of the Microsoft
Windows operating system. Before this, the operating system (DOS) would normallybe controlled via the keyboard. These days it is vital to be a competent mouseuser. There are many different types of mice, a commonly used model now has asmall wheel on it which when combined with the correct software allowsadditional functionally and fine control over the use of your applications.

The Keyboard

The keyboard is still the commonest way of
entering information into a computer. There are a number of different types,
including those specially designed for use with Microsoft Windows. The quality
of the keyboard is often overlooked when buying a PC; it should be robust and
easy to use.

Tracker Balls

A tracker ball is an alternative to the traditional
mouse and favored by graphic designers. Tracker balls often give much finer
control over the movement of the items on the screen. They may take a while to get used to if you are used to the traditional mouse, but offer a lot in terms
of added flexibility

Scanners

A scanner allows you to scan printed material and convert it into a file format
that may be used within the PC. You can scan pictures and then manipulate these inside the PC using a graphics application of your choice. In addition, you can scan printed text and convert this not just to a picture of the text but also
to, actual text that can be manipulated and edited as text within your
word-processor. There are a number of specialist programs, generically called
OCR (Optical Character Recognition) programs that are specifically designed for
converting printed text into editable text within your applications.

Touch Pads

A touch pad is a desktop device and responds to pressure. Used in conjunctionwith a special pen they can be used by graphic artists wishing to createoriginal, digital artwork.

Light Pens


A light pen is used to allow users to point to
areas on a screen and is often used to select menu choices.

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computer memory is measured

Know how computer memory is measured; (bit, byte, KB, MB, GB, TB). Relate
computermemory measurements to characters, files and directories/folders

Basic Units of Data Storage:
It is important to realize that the term digital computer
refers to the fact that ultimately the computer works in what is called binary.
Humans work in tens (because we have 10 fingers). To use the jargon humans work
in base 10. A digital computer uses the numbers 0 and 1 (or on and off if you
prefer). When we talk about computer storage, either the amount of memory (RAM)
or the hard disk capacity we are talking about numbers that are multiples of 0
or 1.

Bit: All computers work on a binary numbering system, i.e. they process data in ones or zeros. This 1 or 0 level of storage is called a bit. Often hardware is specified as a 32-bit computer, which means that the hardware can process 32 bits at a time. Software is also described as 16 bit, 32bit or 64 bit software.

Byte: A byte consists of eight bits.

Kilobyte:A kilobyte (KB) consists of 1024 bytes.

Megabyte: A megabyte (MB) consists of 1024 kilobytes, approximately 1,000,000 bytes.

Gigabyte: A gigabyte (GB) consists of 1024 megabytes, approximately 1,000,000,000 bytes.

Terabyte: A terabyte (TB) consists of approximately 1,000,000,000,000 bytes.

Files: Data and programs are stored on your disk as files. There are different types of files, such as the files that you store your data in, the files that contain your programs and also files used to
store your operating system (such as Microsoft Windows).

Directories (folders):Directories or folders are used to group files with a similar theme together. For example, you could have a folder called “Accounts” containing all your accounting related files, or a folder called “Customers” containing correspondence with your customers. Folders can also contain sub-folders to further divide files. The uppermost level folder is often referred to as the “root” folder (or directory). Sometimes you may see a diagrammatic representation of folders, as illustrated below

In this example, we have the root folder at the top. Below this are three sub-folders called Data, Programs and Games.
Records: A record is a collection of data held within a file. It is the sort of storage unit used by a database. For more information, please see the ECDL module concerned with databases.

computer memory

Understand different types of computer memory such as RAM (random-access memory), ROM (read-only memory) and distinguish between them

What is RAM

Random Access Memory (RAM) is the main
'working' memory used by the computer. When the operating system loads from disk
when you first switch on the computer, it is copied into RAM. The original IBM
PC could only use up to 640 KB of memory (just over half a megabyte), whereas a
modern computer can effectively house as much RAM as you can afford to buy.
Commonly modern computers are supplied with over 128 MB of RAM. As a rough rule,
a Microsoft Windows based computer will operate faster if you install more RAM.
When adverts refer to a computer having 128 Mbytes of memory, it is this RAM
that they are talking about. Data and programs stored in RAM are volatile (i.e.
the information is lost when you switch off the computer).

What is ROM

Read Only Memory (ROM) as the name suggests is a special type of memory chip
that holds software that can be read but not written to. A good example is the
ROM-BIOS chip, which contains read-only software. Often network cards and video
cards also contain ROM chips.

What is the ROM-BIOS

The 'Read Only Memory Basic Input Output System' chip is a chip located on the
computer's system (mother) board, which contains software. This software
performs a variety of tasks. When you first switch on the computer the ROM-BIOS
software performs a self-diagnostic to check that the computer is working OK.
This software then loads your operating system from the disk into the RAM.

What is flash BIOS

Most modern computers are actually supplied with a flash BIOS rather than a
ROM-BIOS. This chip contains exactly the same type of in-built software, but has
the advantage that the software on the chip can be upgraded. This upgrade is
achieved by simply running a small program supplied by the computer
manufacturer.

What is video (graphics) memory

The picture that you see on your screen is a form of data and this data has to
be stored somewhere. The on-screen pictures are held in special memory chips
called video memory chips; these chips are usually located on the video card. A
modern computer will be supplied with several Megabytes of video memory.

Central Processing Unit

(The CPU )

(Central Processing Unit)

The CPU is the brains within your computer. It performs most of the calculations
within the computer and is responsible for the smooth running of

your operating system (Microsoft Windows) as well as your application programs, such
as word-processors, spreadsheets and databases.

There is a small amount of memory associated with the CPU, which it uses to perform
these operations. It also accesses and uses the main

memory(RAM - Random Access Memory) within your computer. In many ways, the CPU is the
single most important item within your computer

that governs the overall speed of your computer. The CPU's speed is measured in MHz.
This relates to the frequency that the CPU runs at and the

higher the MHz rating of your CPU the faster your computer will run. To give you some
indication of how PCs have advanced over the years, the

original IBM PC released in 1981 ran at less than 5 MHz while modern PCs can run at
speeds well in excess of 2000 MHz. Note that 1000 MHz is the same a 1 GHz.

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Memory

What is computer memory

You can store data on your hard disk, while data that is being processed is
stored in RAM (Random Access Memory).

Data that is stored on a hard disk can be permanent, while data in RAM is only
temporary. Normally when people

talk about memory in relation to a PC, they are talking about RAM.

What is Performance ?

Computer Performance

Know some of the factors that
impact on a computer’s performance, such as: CPU speed, RAM size, the ..number of applications running

CPU Clock speed
The computer clock speed governs how fast the CPU will run. The higher the clock speed the faster the computer will work
for you. The clock speed is given in megahertz (MHz). The original IBM PC ran at
4.77 MHz whereas modern PCs will run at over 2000 MHz, which gives you an idea
of how far things have progressed since the introduction of the original PC. The
higher the MHz speed the faster the computer.

RAM size
As a rule the more memory you have the
faster the PC will appear to operate. Windows also uses the hard disk a lot so
logically the faster the hard disk can operate then again the faster the PC will
appear to run

Hard disk speed and storage

Hard disks are also measured by their speed, defined by the disk access time, which
is measured in milliseconds. The smaller this access time the faster the hard
disk will store or retrieve data. The data storage capacity of hard disks
continues to increase as new products are released. The disk storage capacity is
measured in Gigabytes (GBytes). 1 GByte is equivalent to 1024 Mbytes.

Free Hard Disk Space

To get the most out of your Windows based PC, you not only need a fast hard disk but
also a large hard disk with plenty of "spare space". This is due to the fact
Windows is constantly moving data between the hard disk and RAM (Random Access
Memory). Microsoft Windows will create many so-called “temporary files” that it
uses for managing your programs. In fact, if you have very little free hard disk
space you may find that Microsoft Windows will not be able to run your programs
at all.

De-fragmenting Files

If you are running Windows you may
find that if you click on the Start menu, select Programs, and then select the
Accessories / System tools group, there is a de-fragmentation program. Running
this periodically may noticeably speed up the operation of your PC. When you use
a PC, over a period of time the files get broken up into separate pieces that
are spread all over the hard disk. De-fragmentation means taking all the broken
up pieces and joining them back together again.

Multitasking considerations

Windows is a multitasking system, which means that it can run more than one program at a time. However the more programs that are running at the same time, the slower each one will run. To some extent
this slowing effect depends on what each program is doing. Editing a large, full
color picture for instance can take up a lot of CPU time

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Main Parts 5

Modems

A modem is a device that is used to attach your computer to the telephone system. The modem converts data into sound that is sent over the telephone line, the receiving modem turns the sounds back into data. If you wish to connect to the Internet, you will need a modem.

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Printers

Modst data is printed once you have created it and there are a vast number of different printers available to accomplish this. Most common are ink jet and laser printers both of which can now produce colored output (at a cost).



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Scanners

Scanners allow you to scan printed materials into your computer, which can then be stored within the computer. These pictures can then be altered, resized and printed as required.

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Recordable CDs

CD-ROMs are read-only devices, but increasingly people are purchasing a special type of CD drive unit that allows you to record data, music or video to your own CDs. These devices require the purchase of special CDs that you can write to, called CD-R
(Compact Disc – Recordable).

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Tape backup

A tape backup unit allows for regular backing up of your data. These tapes can store a vast amount of data at a low cost. DAT (Digital Audio Tape) devices are commonly used for backups. The DAT tapes that they use can backup enormous amounts of data (i.e. over 4 GBytes per tape). The devices are also fast and reliable.

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PCMCIA

Portables by their very nature are very compact and require smaller than standard parts such as hard disks and CD-ROM drives. Many portables are supplied with special adaptor sockets that enable what are called PCMCIA compatible hardware to be connected to them. PCMCIA components tend to be more expensive than standard computer parts that are designed for more bulky desktop computers


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Main Parts 4

Zip Disc


A Zip disc is like a more recent version of the floppy disk, the main difference being that a single Zip disc can hold up to 250 Mbytes of data. They also offer increased speed compared to the old floppy disk.



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Hard (Fixed) Disk



Hard disks are the main, large data storage area within your computer. Hard disks are used to store your operating system, your application programs (i.e. your word processor, games etc) and your data. They are much faster than CD-ROMs and floppy disks and can also hold much more data.


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The Monitor




An Output device. The monitor is the TV type screen that you view your programs on. They are supplied in different sizes, common sizes range from 15" to 21" screens. You should be aware that poor quality or badly maintained monitors could harm your eyesight


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Additional items or cards


Many 'extra' components can easily be fitted to your computer, which has the advantage of making the computer 'upgradeable' as newer and better hardware comes along.




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Sound cards and speakers

Many computers are now supplied with sound cards and speakers that mean that when you run 'multi-media' programs, you can listen to sounds that are played back via your computer. If you have a microphone and suitable software, you can also record sounds. You can even purchase special software that will allow you to talk to your computer and get the computer to type the words you have spoken on your screen. In time, this type of software may replace the keyboard.

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Main Parts 3

The Keyboard


An Input device. The keyboard allows you to type information into the computer. It has evolved over the years and many people now use a Microsoft style keyboard, which has additional keys designed to make Microsoft Windows easierto use.



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The Mouse



An Input device. When using an operating system, such as Microsoft Windows, you use the mouse to select drop down menus, to point and click on items, to select items and to drag and drop items from one place to another




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CD-ROM
Most computers are now supplied with a CD-ROM (Compact Disc - Read Only Memory) drive. CD-ROM discs look exactly like music CDs but contain computer data instead of music. The advantage of a CD-ROM is that it can hold a vast amount of data (equivalent to the storage capacity of over 450 floppy disks). The other big advantage of CD-ROMs is that they are interchangeable. This means that you can own a range of different CD-ROMs and choose which one to insert into your CD-ROM drive.

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DVD Drives
Short for "Digital Versatile Disc". Similar to CD-ROM drives but allows you to use DVD disks, which contain vastly more information than a traditional CD-ROM disk. These also transfer the data from the disk to the computer far faster, allowing you to watch movies on your computer screen. A CD-ROM can store 650 MB of data, while a single-layer, single-sided DVD can store 4.7 GB of data. The two-layer DVD standard allows a capacity of 8.5 GB. A double-sided DVD increases the storage capacity to 17 GB (or over 25 times the data storage capacity of a CD-ROM).

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Floppy disk



Floppy disks are also known as diskettes. They are very slow compared to hard disks or CD-ROMs, and hold relatively small amounts of data (1.44 Mbytes). Sometimes people will backup (i.e. copy) important data from their hard disk to floppy disks. However, as diskettes are notoriously unreliable this is not the best way of backing up valuable data (but is better than nothing).

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Main Parts 2

ROM-BIOS

The ROM-BIOS (Read Only Memory - Basic Input Output System) chip is a special chip held on your computer's system (mother) board. It contains software that is required to make your computer work with your operating system, for instance it is responsible for copying your operating system into RAM when you switch on your computer

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Serial Port

The serial port is a socket located at the back of your computer that enables you to connect items to the computer, such as a modem. They are commonly labeled as COM1 or COM2

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Parallel Port

The parallel port is a socket located at the back of your computer that enables you to connect items to the computer, such as a printer. It is commonly labeled as LPT1 or LPT2.

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Universal Serial Bus (USB)

The Universal Serial Bus is a relatively new item within the PC. You will see one or more USB sockets at the back of the system unit, allowing you to plug in devices designed for the USB. These devices include scanners and digital cameras

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What are input devices?
Input devices allow you to input information to the computer and include things such as the keyboard and mouse.

What are output devices?
Output devices allow you to output information from the computer and include the printer and the monitor.

What is a peripheral device?
A peripheral device is any device that you can attach to your computer. Thus, you could attach a scanner or modem to the back of your system unit.

Main Parts of a Personal Computer

Know the main parts of a personal computer such as: central processing unit (CPU), hard disk, common input or output devices, types of memory. Understand the term peripheral device.

The System Unit
The "system unit" is the name given to the main PC box

that houses the various elements that go together to make up the PC.

For instance within the system unit is the computer system's motherboard,

which contains all the main components, such as the CPU. The system unit also

houses items such as the hard disk, the floppy disk and CD-ROM drives etc. System

units come in two basic varieties, the tower version, as illustrated

or a desktop version, which is designed to sit on your desk

with your monitor on top of the system unit

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The System (Mother) Board

in contained within your system unit and all the vital computer systems plug directly into the system board. The CPU is normally housed on your system board along with all the other electronic components. Other items such as the hard disk are attached to the system board, either directly or via cables. These boards are getting smaller and smaller as the components become more integrated. If you open up a modern system you will find that it is mainly full of air

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The CPU

The CPU (Central Processing Unit) is normally an Intel Pentium (or equivalent) and it is one of the most important components within your computer. It determines how fast your computer will run and is measured by its MHz speed. Thus, a 2 GHz Pentium is much faster than say a 1 GHz Pentium CPU. It is the CPU that performs all the calculations within the computer, when running programs such as word-processors, spreadsheets and databases. See page 10 for more information.

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Memory (RAM)

The RAM (Random Access Memory) within your computer is where the operating system is loaded to when you switch on your computer and also where your applications are copied to when you start an application, such as a word processor or database program. When you create data, (e.g. letters and pictures), these are initially created and held in RAM and then copied to disk when you save the data. As a rule of thumb, the more RAM you have installed in your computer the better. These days you will commonly find over 128 Megabytes of RAM installed.