ATD Level I
Information Communication Technology cheat sheet
Every chapter's key points, formulas and definitions on one page, for the last week before the exam. Each heading links to the chapter that explains it.
Foundations of computing
- Data is raw, unprocessed facts; information is data processed or organised so that it is meaningful and useful to the person receiving it.
- A computer accepts data, processes it under stored instructions, produces information and stores data for later use; its defining characteristics are speed, accuracy, storage capacity, diligence and versatility.
- A computer system has five elements, hardware, software, data, procedures and people, and removing any one stops it doing useful work.
- Each generation is marked by its core technology: vacuum tubes, transistors, integrated circuits, microprocessors, and now artificial intelligence.
- Computers are classified by size (supercomputer, mainframe, minicomputer, microcomputer), by type (analog, digital, hybrid) and by purpose (general or special).
Key terms
- Data
- Raw, unprocessed facts and figures, for example a list of numbers or names, that carry no meaning on their own until they are processed.
- Information
- Data that has been processed, organised or structured so that it is meaningful and useful to the person receiving it, for example a payroll report produced from raw attendance figures.
- Bit
- A binary digit, 0 or 1, the smallest unit of data a computer can store or process.
- Byte
- A group of eight bits, the basic unit used to measure the size of data and storage (kilobyte, megabyte, gigabyte, terabyte). In binary storage measurement, 1 kilobyte (KB) = 1,024 bytes, 1 megabyte (MB) = 1,024 KB, and 1 gigabyte (GB) = 1,024 MB.
- User
- A person who interacts with a computer system to enter data, run programs or retrieve information.
- Digital
- Represented using discrete binary values (0s and 1s), as opposed to analog, which is represented by a continuously varying signal.
- Supercomputer
- The largest, fastest and most expensive class, used for tasks demanding massive processing power such as weather forecasting and scientific research.
- Mainframe
- A large, powerful computer used by big organisations to process and store vast volumes of data centrally, for example a bank's core transaction system.
- Minicomputer
- Mid-sized, less powerful than a mainframe but capable of supporting multiple users at once, typically for a department rather than an entire organisation.
- Microcomputer
- The smallest and most common class, built around a single microprocessor, including desktops, laptops, tablets and smartphones.
- Analog computer
- Processes continuously varying physical quantities (voltage, temperature, pressure) directly, used mainly in scientific and industrial measurement.
- Digital computer
- Processes data represented as discrete binary values; this is the class covered by the rest of this paper.
- Hybrid computer
- Combines analog input (for example, a continuous sensor reading) with digital processing, common in medical equipment such as an ECG monitor.
- General purpose computer
- Designed to run many different kinds of program, from word processing to accounting to games, the class almost every desktop and laptop belongs to.
- Special purpose computer
- Built and programmed for one specific task only, for example the embedded computer that controls a washing machine or an ATM.
The rest of the sheet covers
- Computer hardware
- Computer software
- Computer networks
- Exam technique and revision
- Glossary