Macquarie Fields College of TAFE

Macquarie Fields College of TAFE

Version 2 – 13 March 20003 - HARDWARE

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Types of Computers

• Minicomputers– Powerful– General Purpose– 50/100 MIPS

• Microcomputers– Single silicon chip

(CPU)• Desktop/Laptop

– 5/20 MIPS

• Super computers– 250 MIPS– Multiple Processors

• Mainframes– Large & Fast– Networked 100/200

MIPS


Issues Surrounding Computers

• Cost

• Security/Passwords

• Customisation

• Ease of use

• Performance


Monitors (VDU)• Another term for display screen. The

term monitor, however, usually refers to the entire box, whereas display screen can mean just the screen. In addition, the term monitor often implies graphics capabilities.

• There are many ways to classify monitors. The most basic is in terms of colour capabilities, which separates monitors into three classes.


Monitors - Colour• Monochrome

Monochrome monitors actually display two colours, one for the background and one for the foreground. The colours can be black and white, green and black, or amber and black.

• Gray-scale

A gray-scale monitor is a special type of monochrome monitor capable of displaying different shades of gray.


Monitors - Colour

• Colour

Colour monitors can display anywhere from 16 to over 1 million different colours. Colour monitors are sometimes called RGB monitors because they accept three separate signals -- red, green, and blue.


Monitors - Size• screen sizes are measured in diagonal

inches, the distance from one corner to the opposite corner diagonally.

• A typical size for small VGA monitors is

14-15 inches.

• Monitors that are 16 or more inches diagonally are often called full-page monitors.


Monitors - Resolution• The resolution of a monitor indicates

how densely packed the pixels are. In general, the more pixels (often expressed in dots per inch), the sharper the image.

• Most modern monitors can display 1024 by 768 pixels, the SVGA standard. Some high-end models can display 1280 by 1024, or even 1600 by 1200.


PrintersA printer is a peripheral device that is

attached to a computer and is used to transfer data from the computer to

paper producing a hard copy.


The printer uses a parallel connection that has 25 pins. This is used so that the information can be processed at 8 bits (1 byte) at a time.

Types of Printers

• Impact

– Dot Matrix

– Daisy Wheel

• Non-impact

– Laser

– Ink jet/bubble jet

– Plotter


Which printer should I get?

Printers are designed for just about everybody and everything – from black

and white to architectural design, colour printouts or high quality designs.

Let’s look at the advantages and disadvantages of the types already

discussed.


Advantages/Disadvantages of Different Printers

LASER PRINTER• Advantages

High quality printoutsFastReasonably pricedQuiet

• DisadvantagesCostly to maintain - Expensive to replace cartridges and the number of output is half to inkjetBulky in size



INK JET/BUBBLE JET• Advantages

Reasonable qualityCost EffectiveQuietFast

• DisadvantagesInk will run if wetCartridges can be expensive to replace



PLOTTER• Advantages

Can print larger than A3 paperCan print in thin intricate lines used for 3D, map and design drawings

• DisadvantagesExpensive to purchaseSlow to print



DOT MATRIX/DAISY WHEEL• Advantages

- Can print multiple copies as the impact printer strikes carbonised sets

• Can print continuous paper• Disadvantages

- Slow- Noisy- Ribbons are becoming more expensive as machines are becoming more extinct


ASCIIAmerican Standard Code for Information Interchange

• Represents all letters, numbers and characters on keyboards

• 01000001= A

• 01010100= T

• 8 bits = 1 byte = 1 character



• There are 256 possible combinations of ASCII code. The ASCII character set shown here represents the capital letter ‘A’ as 65, ‘T’ as 84, lower ‘a’ as 97 and ‘½’ as 171.




128 64 32 16 8 4 2 1

0 1 0 0 0 0 0 1 65 A 01000001

0 1 0 1 0 1 0 0 84 T 01010100

0 1 1 0 0 0 0 1 97 a 01100001

1 0 1 0 1 0 1 1 171 ½ 10101011


0 1 0 0 0 0 1 0


1 Bit

1 Byte

(Binary Digit)

MemoryUnits of Measurement


1 BIT = 0’s or 1’s8 BITS = 1 BYTE (1 character)1,000 BYTES = 1 KILOBYTE (1 thousand)1,000 KILOBYTES = 1 MEGABYTE (1 million)1,000,000

1,000 MEGABYTES = 1 GIGABYTE (1 billion)1,000 million 1,000,000,000

1,000 GIGABYTES = 1 TERABYTE (1 trillion)1 million million (1012)

÷

Security

Refers to techniques for ensuring that data stored in a computer cannot be read or compromised. Most security measures

involve data encryption and passwords. Data encryption is the translation of data into a

form that is unintelligible without a deciphering mechanism. A password is a secret word or phrase that gives a user

access to a particular program or system.


Passwords

A secret series of characters that enables a user to access a file, computer, or program.

On multi-user systems, each user must enter his or her password before the

computer will respond to commands. The password helps ensure that unauthorized

users do not access the computer. In addition, data files and programs may

require a password.


Security/Passwords

• Encryption

• Passwords

• Security Levels

• Attributes

• Backups


Documents

Macquarie Fields College of TAFE