GCSE ICT/GCP Revision Guide
Section One- What is A Computer?
Data
Data has NO MEANING
- Data is information that has no meaning.
- Data only becomes information when you know the context of the data.
- Information = Data + Meaning
Data is stored in Bytes
- Computers use a binary code (i.e. they use only 2 digits) to represent data. Usually, a circuit that's switched on represents the digit 1, and a circuit that's switched off represents the digit 0.
- Bit: Each individual 1 or 0 is called a bit - short for binary digit.
- Byte: 8 bits is called a byte.
- Kilobyte: 1 kilobyte (1 KB, or simply 1 K) is about a thousand bytes. to be exact, 1KB = 2 to the power of 10 = 1024 bytes.
- Megabyte: 1 megabyte (1MB) is about a million bytes. To be exact, 1 KB = 2 to the power of 20 = 1048576 bytes.
Computer System
Data is entered at the input stage
- information is converted into data before its entered into the computer
The computer then processes the data
- Processing involves turning the input data into something else
The results are then sown at the output stage
- Output is when the computer communicates the results of the data processing to the user.
- The two most common ways are a screen display and printed paper.
- At this point the data becomes information again
- The information obtained at the output stage might then be used as feedback to input more data. this turns the system into a cycle.
9-Input Devices
An input device is any hardware which is used to enter data into the computer system. The input devices of a computer are
- QWERTY Keyboard
- Mouse
- Camera
- CD
- Microphone
- Scanner
- Disk Drive
- Joystick
12-The CPU
CPU stands for Central Processing Unit
- The CPU is the portion of a computer system that carries out the instructions of a computer programs
Section Three- Using a A computer System
Section Four- System Analysis
Section Five- Text and Image Processing Software
Section Six- Spreadsheets and Database
The Basics
Spreadsheets are clever calculators
- A spreadsheet is a program that can display and process data in a structured way.
- Spreadsheets can process numbers and also handle text.
- spreadsheets can be used to:record data, search for particular items of data, perform calculations based on data, produce graphs and charts.
Data is entered into cells
- Spreadsheets are formed by tables- rows and columns divide them selves in to cells.
- Each cell can be recognized by using coordinates by using the row number and column letter.
Each cells can contain one of three things
Cells can only contain one thing of these three things
- Numerical Data- for example numbers, money and dates
- Text Data
- Formulas
Graphs and Charts
Section Seven- Measurement, Control and simulation
Section Eight- The Internet
Internet Basic
- The Internet is an International Network of computers
To connect you need Special Hardware and Software:
- Most people access the internet using a PC conneted to a telephone cable or cable TV services these two items can not work without a modem. A modem converts data from the computer into a format suitable for sending over the telephone or other communication line. Both ends of the connection need a modem.
- The Internet Has Two Main Parts:
1) The World Wide Web (WWW) is the part that contains web pages. 2) Electronic Mail(E-MAIL) is the part where messages are sent from one person to another - it works a bit like sending a letter.
- There is 5 step to sending an E-mail
Step 1-Create the message Step 2-Connect to the Internet Step 3-Press the send button Step 4-The message is sent from the sender's ISP to a mailbox in the computer system of the recipient's ISP Step 5-The recipient later connects to the internet, opens their e-mail account, and finds the new message
- Emails has Benfits and Problems
Emails take quick to send It is cheaper than posting or faxing The same message can easily be sent to loads of diffent people Both need Internet access and Email accounts
- The Internet is a huge Source of Information
You can access the Internet form any computer, the Information is up to date.
- Type in the URL
URL stands for Uniform Resource Locator URLS's can not cantain capital letters or spaces or certain types of punctuation
Computers And The Law
Computer are used to store and process important data. As it is easy to transfer data through the internet. So there are laws to protect the use of computers
The Copyright, Design and Patents Act Controls Illegal copy
This law was introduced in 1989, this law made it so that it was illegal to copy a file without permission from the owner, or copyright user.
Three ways that this law is broken up into:
- Using software without a proper licence. E.g. if you acquire a MS software disk and upload it onto one computer station, it is illegal to use it on any other computer station.
- Downloading text or images without saying where you have gotten it from, or with receiving the copyright owner's permission.
- Copying a computer program that you use at another place and running at a computer at home without the permission from the copyright holder.
The computer misuse act prevents illegal Access to files
This law was introduced in 1990 to stop hackers and viruses. The act made the following three things illegal:
- Unauthorised access to computer material. E.g. hacking
- Attainment of unauthorised access to a computer to carry out serious offence such as fraud and blackmail.
- Unauthorised changing of computer files. E.g. planting viruses and deleting files