Part A: Computers
Foundations of computing
Key takeaways
- 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).
This chapter sets out the vocabulary the rest of the paper assumes: what a computer is, how it differs from computing as an activity, the five elements that make up a computer system, and the generations and classifications used to describe computers. Get this chapter right and every later chapter on hardware, software and networks reads as an application of it.
Key terms
Computer
A computer is an electronic device that accepts data as input, processes it according to a set of stored instructions, and produces information as output, while storing data and instructions for later use. Its defining characteristics are:
- Speed: millions of operations per second.
- Accuracy: near-zero error when correctly instructed and fed correct data.
- Storage capacity.
- Diligence: it does not tire or lose concentration over repetitive tasks.
- Versatility: the same machine can run a payroll, mark an exam or edit a photograph, depending only on the program loaded.
Computing is wider than the computer. It covers the whole activity of using computers to capture, process, store and communicate information, including the people who do it, the procedures they follow and the data they work with. The distinction matters in an exam answer: a computer is a machine, while computing is what an organisation does with it.
Computing
Computing is the activity of using and developing computer technology, hardware and software, to process data, solve problems and manage information. Where a computer is a physical device, computing is the broader discipline: designing algorithms, writing programs, managing networks and analysing data are all computing, whether or not a single machine is in view at the time.
Computer system
A computer system is a complete, working combination of five elements, and removing any one of them stops the system from doing useful work.
- Hardware: the physical components of the machine.
- Software: the programs that instruct the hardware what to do.
- Data: the raw facts the system processes.
- Procedures: the documented steps and rules for using the system correctly.
- People (users): the individuals who operate the system, from data-entry clerks to system administrators.
A computer system is best understood as a cycle of input, processing, output and storage, with each stage handled by different components. Data enters through input devices, is transformed by the processor according to the instructions in software, is presented through output devices, and is kept for later use in storage. A fault or bottleneck at any stage limits the whole system, which is why a fast processor paired with slow storage still feels slow to its user.
Hardware
Hardware is the physical, tangible part of a computer system, everything that can be touched: the case, the motherboard, the processor, the keyboard, the monitor and every other physical component. Hardware on its own cannot do anything useful; it needs software to instruct it.
Software
Software is the collection of programs, procedures and associated data that instruct computer hardware what to do and how to do it. Software is intangible, it cannot be touched, only stored on and read from a physical medium, and it is what turns general-purpose hardware into a tool for a specific task.
Program
A program is a set of step-by-step instructions, written in a programming language, that tells a computer how to perform one specific task, for example sorting a list of names or calculating a total. Software is the broader term: a piece of software, a word processor for example, is normally made up of many programs plus the data and documentation that support it.
Information communication technology
Information Communication Technology (ICT) is the combination of computing technology (hardware and software for processing data) with telecommunications technology (equipment and networks for transmitting data), covering everything used to create, store, process, transmit, retrieve and exchange information electronically, from a single desktop computer to the global Internet.
Computer generations
Computers are grouped into five generations, each marked by a leap in the core technology used to build them.
| Generation | Core technology | Approximate period | Notable feature |
|---|---|---|---|
| First | Vacuum tubes | 1940s to mid-1950s | Huge, generated enormous heat, and used machine language directly; example: ENIAC. |
| Second | Transistors | Mid-1950s to mid-1960s | Smaller, faster and more reliable than vacuum tubes, and programmed in early high-level languages such as COBOL and FORTRAN. |
| Third | Integrated circuits (ICs) | Mid-1960s to mid-1970s | Many transistors etched onto a single chip, giving a further jump in speed and reliability and the first use of operating systems. |
| Fourth | Microprocessors (VLSI) | Mid-1970s to late 2000s | An entire processor on one chip, making the personal computer possible; most desktops and laptops in use today are fourth-generation machines. |
| Fifth | Artificial intelligence | Present and emerging | Built around parallel processing, natural language processing and machine learning, aiming for machines that can reason and learn rather than simply execute fixed instructions. |
Computer generations are defined by the switching technology each used, and the pattern across them matters more than the dates. Each generation made computers smaller, faster, cheaper, more reliable and less power-hungry than the last, and each widened who could use them: from room-sized machines operated by specialists, to minicomputers in large organisations, to personal computers on desks, to the phones in people's pockets. The practical lesson for a business is that computing power once reserved for large firms is now affordable to the smallest enterprise.
Classification of computers
By size
Classification by size reflects processing power and the number of users served. Supercomputers handle extremely demanding calculations such as weather forecasting. Mainframes serve very large numbers of simultaneous users in organisations such as banks and government agencies, where reliability and volume matter most. Servers provide shared services to other computers across a network. Personal computers, laptops, tablets and smartphones serve individual users. The boundaries have blurred as smaller devices have grown more powerful.
By type
Classification by type distinguishes:
- Digital computers, which process discrete values and are the kind used in business.
- Analogue computers, which process continuously varying quantities such as temperature or voltage.
- Hybrid computers, which combine both, as in some medical and industrial monitoring equipment.
By purpose
Converting between storage units
A video file is reported as 4,600 MB. Convert this to gigabytes, using 1 GB = 1,024 MB.
4,600 MB / 1,024 = 4.49 GB (to two decimal places).
A separate figure quotes a connection's speed as 800 kilobits per second (kbps). Since 1 byte = 8 bits, this converts to 800 / 8 = 100 kilobytes per second (KB/s), the unit more directly comparable to a file size given in KB or MB.
This bits-versus-bytes distinction is a common source of confusion: a connection advertised as '100 Mbps' transfers at only 100 / 8 = 12.5 megabytes per second, not 100 megabytes per second.
Classification by purpose separates general-purpose computers, which can run many different programs, from special-purpose computers built for a single task, such as the controller in a fuel pump or an automated teller machine. Most computers a business buys are general-purpose; special-purpose computers are usually embedded inside other equipment.
Exam tip
'Hardware', 'software' and 'program' are the trio examiners most often blur together in a question. Hardware is what you can touch; software is the full collection of programs, data and documentation that instructs it; a program is one specific set of instructions within a piece of software.
Self-check
(a) A document library totals 3,200 MB. Convert this to gigabytes, using 1 GB = 1,024 MB. (3 marks)
(b) Distinguish between data and information, giving one example of each drawn from a school's student records. (4 marks)
(c) State the five characteristics that define a computer, and explain why 'versatility' specifically distinguishes a computer from a special-purpose electronic device like a calculator. (5 marks)
(d) List the five elements of a computer system, and explain what happens to the system's usefulness if the 'procedures' element is missing while the other four remain intact. (5 marks)
(e) Distinguish between the third and fourth generations of computers, identifying the specific technological leap between them. (3 marks)
Show worked answer
(a) 3,200 MB / 1,024 = 3.13 GB (to two decimal places). (3 marks)
(b) Data is raw, unprocessed facts and figures that carry no meaning on their own, for example a raw list of student exam scores with no names attached. Information is data that has been processed, organised or structured so it is meaningful and useful, for example a class ranking report showing each named student's average score and position. The raw scores become information once they are organised, attributed to specific students, and presented in a way that supports a decision (identifying who needs extra support). (4 marks)
(c) Speed (millions of operations per second), accuracy (near-zero error when correctly instructed and fed correct data), storage capacity, diligence (does not tire or lose concentration over repetitive tasks), and versatility (the same machine can run many different kinds of program depending only on what is loaded). Versatility distinguishes a computer from a special-purpose device like a calculator because a calculator is built and permanently wired to do arithmetic only, it cannot be reprogrammed to word-process or edit a photograph, whereas a computer's hardware is general-purpose and can be made to perform an entirely different task simply by loading different software. (5 marks)
(d) Hardware, software, data, procedures, and people (users). If procedures, the documented steps and rules for using the system correctly, are missing while the other four elements remain intact, the system's physical and technical capability is unaffected, but users have no consistent, correct way to actually operate it, leading to inconsistent use, avoidable errors, and a greater risk of data being entered, processed or stored incorrectly, even though every other component is technically present and working. (5 marks)
(e) The third generation was built on integrated circuits (ICs), many transistors etched onto a single chip, giving a jump in speed and reliability and the first use of operating systems, but a computer of this generation was still typically a large, room-sized machine. The fourth generation was built on microprocessors (VLSI), an entire processor fitted onto one single chip, the specific leap that made the personal computer possible, shrinking a machine that once filled a room down to something that could fit on a desk. (3 marks)