Wednesday, November 11, 2009
Types of computer
these are the fastest and the most expensive computers available and could cost over 100 million pounds. They are mainly used for advanced scientific research, weather forecasting or advanced engineering applications.
Main-frame computers -
these are capable of processing and storing huge amounts of data. They would be used by large utility companies such as gas suppliers as well as banks etc.
Minicomputers - these may be used by smaller businesses to manage their data processing or to run something like a city traffic control system.
Microcomputers - these systems such as typically used by home and school users. They can be divided into different types:
Desk top computers - these would typically be supplied with the computer itself (complete with hard disk drive and floppy disk drive) and peripherals such as a screen, a mouse, a keyboard and a CD or
DVD drive.Advantages: Relatively cheap and easy to add expansion cards to.
Disadvantages: Can take up a lot of space and are not easily moved.
Notebooks (laptops) - these are small (typically 30cm x 20cm), light and easy to carry. The screen is on the inside top flap which hinges open to show the keyboard and mouse controls. They are designed to run on rechargeable batteries or the mains and can contain many of the features available on a desktop computer. Touch pads or a button are usually used to control the screen pointer.
Advantages: Portable due to their size and ability to run on batteries.
Disadvantages: Expensive for their processing power compared to desktop computers. You cannot use standard expansion cards. Keyboards and screens not as good for extended usage.
Palm-tops & PDAs (personal digital assistants) - These are small hand-held computers. They are usually supplied with software such as a diary, a contacts database, and some form of word processor. Many now have email facilities and even spreadsheets and databases. They either use a small keyboard or a touch-sensitive screen and handwriting recognition software. They can be linked to larger co
mputers directly by cable or through a docking station or using an infra-red link.Advantages: Very portable.
Disadvantages: Relatively expensive, limited expansion, non-keyboard versions can be slow to input data.
A vast number of modern devices contain some form of built-in computer. Examples include: washing machines; camera, hi-fi systems; telephones; microwave ovens; missiles etc. etc. The inputs are usually sensors so a keyboard may not be needed. The outputs are usually simple displays or motors and relays to control something
TASK
Arrange the following statements into the advantages or disadvantages of the different computers. (some of the statements can be used for more than one type of computer)
1. Can use many different types of software 2. Can only use very limited software such as email or diary events 3. Portable
4. Light to carry 5. Fits in your pocket 6. Around £1000
7.Around £1500 - £2000 to buy 8.Can easily be broken 9.Easy to upgrade or expand
10.Cannot upgrade 11.Very difficult to expand 12.Easy to steal
13.No mouse but touch-pad or button control 14.Stylus control 15.Mouse control
16.Ergonomically designed 17.Uncomfortable to use for long periods of time 18.Can run on electricity or battery
19.Standard equipment for businesses, schools and home 20.Not as powerful as a desk-top PC 21.Very strong
22.Around £500 to buy 23. No keyboard – handwriting recognition used 24. Difficult to move around
Desk-Top PC Notebook PDA
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What does the term PDA mean and what other phrase is used to describe similar types of computers?
3. Imagine you have an older friend who is moving away to University soon. They want to buy a new computer to take with them – remembering of course that they must come home for every holiday. Which type of computer would you suggest – explain fully your answer – why would you suggest that type? (There is no right or wrong answer here as long as you explain fully!)
computer
manipulates it for some result based on a program or sequence of instructions on how the data
is to be processed. Complex computers also include the means for storing data (including the
program, which is also a form of data) for some necessary duration. A program may be
invariable and built into the computer (and called logic circuitry as it is on microprocessors)
or different programs may be provided to the computer (loaded into its storage and then
started by an administrator or user). Today’s computers have both kinds of programming.
Most histories of the modern computer begin with the Analytical Engine envisioned by
Charles Babbage following the mathematical ideas of George Boole, the mathematician who
first stated the principles of logic inherent in today’s digital computer. Babbage’s assistant and
collaborator, Ada Lovelace, is said to have introduced the ideas of program loops and
subroutines and is sometimes considered the first programmer. Apart from mechanical
calculators, the first really useable computers began with the vacuum tube, accelerated with
the invention of the transistor, which then became embedded in large numbers in integrated
circuits, ultimately making possible the relatively low-cost personal computer.
Modern computers inherently follow the ideas of the stored program laid out by John von
Neumann in 1945. Essentially, the program is read by the computer one instruction at a time,
an operation is performed, and the computer then reads in the next instruction, and so on.
Recently, computers and programs have been devised that allow multiple programs (and
computers) to work on the same problem at the same time in parallel. With the advent of the
Internet and higher bandwidth data transmission, programs and data that are part of the same
overall project can be distributed over a network and embody the Sun Microsystems