Transcript Document
Macquarie Fields College of TAFE
3
Version 2 – 13 March 2000 3 - HARDWARE
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Types of Computers
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Super computers
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250 MIPS
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Multiple Processors Mainframes
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Large & Fast
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Networked 100/200 MIPS
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Minicomputers
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Powerful
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General Purpose
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50/100 MIPS Microcomputers
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Single silicon chip (CPU) Desktop/Laptop
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5/20 MIPS
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Issues Surrounding Computers
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Cost Security/Passwords Customisation Ease of use Performance
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Monitors (VDU)
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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.
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There are many ways to classify monitors. The most basic is in terms of colour capabilities, which separates monitors into three classes.
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Monitors - Colour
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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.
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Gray-scale A gray-scale monitor is a special type of monochrome monitor capable of displaying different shades of gray.
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Monitors - Colour
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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.
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Monitors - Size
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screen sizes are measured in diagonal inches, the distance from one corner to the opposite corner diagonally .
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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.
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Monitors - Resolution
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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.
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Printers
A 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.
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Types of Printers
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Non-impact
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Laser
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Ink jet/bubble jet
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Plotter
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Impact
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Dot Matrix
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Daisy Wheel
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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.
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Advantages/Disadvantages of Different Printers
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LASER PRINTER
Advantages High quality printouts Fast Reasonably priced Quiet Disadvantages Costly to maintain - Expensive to replace cartridges and the number of output is half to inkjet Bulky in size
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Advantages/Disadvantages of Different Printers
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INK JET/BUBBLE JET
Advantages Reasonable quality Cost Effective Quiet Fast Disadvantages Ink will run if wet Cartridges can be expensive to replace
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Advantages/Disadvantages of Different Printers
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PLOTTER
Advantages Can print larger than A3 paper Can print in thin intricate lines used for 3D, map and design drawings Disadvantages Expensive to purchase Slow to print
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Advantages/Disadvantages of Different Printers
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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
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ASCII
American Standard Code for Information Interchange
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Represents all letters, numbers and characters on keyboards 01000001 01010100 = = A T 8 bits = 1 byte = 1 character
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ASCII
American Standard Code for Information Interchange
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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.
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ASCII
American Standard Code for Information Interchange
128 64 32 16 8
0 0 1 0 0 1 0 1 0 0 0 1 1 0 1 1 0 0 0 1
4
0 1 0 0
2
0 0 0 1
1
1 0 1 65 A 01000001 84 T 01010100 97 a 01100001 1 171 ½ 10101011
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ASCII
American Standard Code for Information Interchange
1 Byte
0 1 0 0 0 0 1 0
1 Bit
( B inary Dig it )
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Memory
Units of Measurement
1 BIT = 0’s or 1’s 8 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 (10 12 )
÷
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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.
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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.
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Security/Passwords
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Encryption Passwords Security Levels Attributes Backups