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Transcript of igcse ict
These are the most common input devices.
Most people find them easy to use.
Keyboard are fairly large.
The Mouse is an example of a pointing device.
Mice take a little area.
Can give you a finger/hand ache.
By: Dimas Piqueras
Trackerballs are similar to mice.
Don’t need the same fine control as in mice.
May need training.
Can be connected directly to a computer.
It is faster to read in text than typing it.
Sound files use up lots of memory.
A remote control is used to control the operation of other devices remotely by using infra-red signals.
Remote controls enable to operate by a distance.
Can be find difficult to use because of so many buttons.
WebCams are simiral to video cameras.
WebCams can be left on constantly.
WebCams have very limeted features.
Touchpads are used in many laptop computers.
They can be used even in non-flat surfaces.
The pointer is more difficult to use than a mouse.
A numeric pad is used to enter numbers only.
Are faster than keyboards for entry of numeric data.
It is difficult to use them for entering text.
Similar functions to mice and trackerballs.
Control is in 3D.
It is harder to use.
Hardware and software:
Computer hardware is any physical device, something that you are able to touch and software is a collection of instructions and code installed into the computer and cannot be touched. For example, the computer monitor you are using to read this text on and the mouse you are using to navigate this web page is computer hardware. The Internet browser that allowed you to visit this page and the operating system that the browser is running on is software.
Main components of computer systems
CPU: The most important component of a computer system is the CPU, or central processing unit, which consists of the Motherboard, hard drive, and connector cables.
Operating Systems:The Operating System runs the software on your computer, provides security and tracks other programs to ensure compatibility. Examples include Microsoft Windows, Linux or Apple's Macintosh.
Systems analysis and design
A systems analysisi team is often brought in to review an existing system and suggest a number ofimprovements. The existing method used used may be eather a manual paper-based system or a computer-based operation that is no longer regarded as adequated for the task.
facts finding/collection data from the current system
Description of the current system -establishing the inputs, ouputs and processing being done.
identification of the problems with the current system
agreeing the objectives with the custoimer
identifying and agreeing the customer´s requirements
Once the analysis has taken place and the system analyst has some idea of the scale of the problem and what needs to be done, the next stage is to
the key parts of the recommend system.
Development and testing
Once the design stage is completed, it is the necessary to create the system and fully test it. the section considers some of the development stages and testind strategies which are often adodepted by systems analysts.
Once the system is fully tested, the next stage is to fully implement it. We will now consider
to the new system in more depth. There are 4 common methods used for changing over from the old system to the new system. Each one has advantages and disadvantages.
Once the new system
*these systems have been developed to mimic the expertise and knowledge of an expert in a particular field:
+diagnosing a person´s illness
+prospecting for oil and minerals
+tax and financial calculations
:design and creativity.
design and creativity.
is designed and created
-expert systems provide consistent answers
-it can be expensive to set up the first place
storage devices and media
A storage device may hold information, process information, or both. A device that only holds information is a recording medium. Devices that process information (data storage equipment) may either access a separate portable (removable) recording medium or a permanent component to store and retrieve information.
rendering a video
Faster data retrieval
Easy expansion (Add a table)
All other data is up to date once an update is made as data is not repeated
A foreign key in one table is a primary key in another
Relational databases cont.
Introduced in 1970
A number of tables
Combine data from different tables to create a report
No need to repeat data
Where is adc used in a central heating system?
Where is dac used in a central heating system?
Computers only understand digital
Must use an adc
If a computer is used to control an analogue device then a digital to analogue converter is required
Analogue to digital Converter (AdC)
How do we know the values…
Position of pointer on a dial
Height of liquid
Sensors measure these physical, analogue quantities
Discrete, fixed values in a given range
Real world data
Infinite number of values within a given range
Length, Weight, Temperature, Pressure
Analogue & digital data
Structured to allow
Up to date info for external applications
Data duplication minimised
Easy to expand
Secure as controlled by front end
Used to locate a record in a file
Primary Key / Key field
Whole numbers (+ive or –ive)
True / False
Yes / No
1 / 0
AND – True for both cases
OR – true for at least one case
Logical / Boolean
Contains all the data in one table
Flat file structure
DD mmmm yyyy
A to Z
A to Z anD 0 to 9
Logical / Boolean
Alphanumeric / Text
Data stored in files
Files consist of records
RecorDs contain fields