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| Question | Answer |
| IGCSE IT Revision | Theory notes units 1-8 |
| Central processing unit | The CPU is the 'brain' of the computer. It is the device that carries out software instructions |
| Random Access Memory (RAM) | Random Access Memory (RAM) is the part of the computer that temporarily stores the instructions that the computer is running, and the data it is processing. |
| Read-Only Memory (ROM) | Read-Only Memory (ROM) is used in most computers to hold a small, special piece of software: the 'boot up' program. This software runs when the computer is switched on or 'boots up'. The software checks the computer’s hardware and then loads the operating system. ROM is non-volatile storage. This means that the data it contains is never lost, even if the power is switched off. |
| What Are Input Devices? | Devices that pass data into the computer are known as input devices. A keyboard, a mouse and a webcam are all examples of input devices. |
| What Are Output Devices? | Devices that take data from the computer are known as output devices. A monitor, a printer and a loudspeaker are all examples of output devices. |
| What is an Operating System? | An operating system is a special piece of software that manages the general operation of a computer system |
| Graphical User Interface (GUI) | A GUI is an interface built around visual (graphical) things GUIs are quite easy to use due to the visual nature of the interface – the user has lots of visual clues as to what things do. |
| Command Line Interface (CLI) | Many years ago when computers were not very powerful they could not display the colourful graphics required for a GUI. The only interface available to most computer uses was the ‘command line’ |
| Mainframe Computer | A mainframe computer is a large computer, often used by large businesses, in government offices, or by universities Powerful - they can process vast amounts of data, very quickly •Large - they are often kept in special, air-conditioned rooms •Multi-user - they allow several users (sometimes hundreds) to use the computer at the same time, connected via remote terminals (screens and keyboards) |
| Integers | An integer is a whole number - it has no decimal or fractional parts. Integers can be either positive or negative |
| Peripheral Devices | Technically, a computer need only be made up of a CPU and some RAM. But a computer like this would not be much use to anybody – other devices need to be connected to allow data to be passed in and out of the computer. The general name for these extra devices is ‘peripheral devices’. They are usually categorised into input devices, output devices and storage devices |
| Boolean | Boolean data is sometimes called 'logical' data (or in some software, 'yes/no' data). Boolean data can only have two values: TRUE or FALSE |
| Numeric Data | Numeric data simply means numbers. But, just to complicate things for you, numbers come in a variety of different types... |
| Alphanumeric (Text) Data | Alphanumeric (often simply called 'text') data refers to data made up of letters (alphabet) and numbers (numeric). Usually symbols ($%^+@, etc.) and spaces are also allowed |
| What is a Record | The set of data associated with a single object or person is known as a record |
| What is Systems Analysis? | 1. Analysis 2. Design 3. Implementation 4. Documentation 5. Evaluation |
| What is a Microprocessor? | A microprocessor is a small CPU built into a single 'chip' (see right). |
| What is Hacking? | The word 'hacking' has several meanings, but in the context of ICT, it is normally taken to mean breaking in to a computer system. |
| What is Malware? | Malware is short for malicious software. |
| What is a Computer Virus? | A computer virus is a piece of software that can 'infect' a computer (install itself) and copy itself to other computers, without the users knowledge or permission. |
| What is Software Copyright? | When someone creates an original piece of software, that person then holds something called the copyright for that software. (This is also true when people create books, films and songs.) Holding the copyright for software means that you have the protection of the law if anyone tries to steal your software. |
| Phishing | 'Phishing' is the nickname given to the sending of fraudulent e-mails that attempt to trick people into revealing details about their bank accounts, or other online accounts (e.g. Amazon, eBay, etc.) |
| Pharming | 'Pharming' is similar to phishing, but instead of deceiving you (as phishing does), a pharming attack deceives your computer. In a pharming attack, when you type in a completely genuine URL (e.g. for your online banking website), your computer is tricked into displaying a fake website (often a very accurate copy). |
| Real Numbers | Any number that you could place on a number line is a real number. Real numbers include whole numbers (integers) and numbers with decimal/fractional parts. Real numbers can be positive or negative. |
| Currency | Currency refers to real numbers that are formatted in a specific way. Usually currency is shown with a currency symbol and (usually) two decimal places |
| Percentage | Percentage refers to fractional real numbers that are formatted in a specific way - out of 100, with a per cent symbol |
| Date and Time Data | Date (and time) data is usually formatted in a specific way. The format depends upon the setup of the computer, the software in use and the user’s preferences |
| Flat-File Databases | A 'flat-file' database is one that only contains a single table of data |
| Relational Databases | A 'relational' database is one that contains two or more tables of data, connected by links called relationships. |
| Internet Banking | Compared to traveling to your actual bank, Internet banking has a few advantages... •More convenient - can be used 24 hours a day, 7 days a week •Saves time and money since you don't have to travel anywhere to use it •Data can be downloaded and analysed (e.g. in a spreadsheet) which can help with planning budgets But there are some disadvantages too... •Requires you to have a computer and Internet access to use it •Some people prefer to speak to a person (personal service) •If your account is hacked, or your username / password is stolen (e.g. if your computer has malware) money could be stolen from your account |
| Batch Processing | this is where a number of similar jobs or tasks are collected together(batched) and processed by a computer all at once rather than individually |
| Online Processing | this type of processing is where a user communicates directly with the computer system |
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