05 Software, translators and development

GCSE Computer Science 1CP2

Anti-malware

utility software that detects and provides protection against attacks from malicious software.

Application software (apps)

programs designed for end users such as a web browser, an email client or a spreadsheet.

Assembly language

a low-level language written using mnemonics. Each instruction in assembly language is equivalent to one machine code instruction.

Boundary data

data that sits on the edge of any test conditions, either above or below.

Breakpoint

a mechanism to mark a line of code, where execution is paused, if using a debugger.

Bug

an error in program code.

Central processing unit (CPU)

the hardware component that carries out the processing in a computer.

CLI

command-line interface, which enables a user to interact with the computer by typing in commands.

Cloud computing

the storing of software and data on remote servers accessed through the internet.

Code vulnerability

a flaw ina program that compromises security, enabling an attacker to gain access to a computer system and the data within it.

Compiler

a translator that converts high-level language source code into machine code. The source code is translated all at once and saved as object code to be executed later.

Console

the place where the output from a program is displayed. This could be directly on a device or in a window of another application, such as an IDE.

Cross compiler

is capable of generating code for a computer type other than the one it is running on.

Debug

the process by which a programmer finds and corrects errors in code.

Device driver

a program that relays instructions and data between the operating system and a peripheral device. Each device has its own driver. Digital device - a physical unit of equipment that contains a computer or microcontroller such as a smartphone, tablet, smartwatch, laptop computer and digital assistants such as Amazon Echo and Google Home.

Disk defragmenter

a tool that moves file blocks on a disk, so they are closer to each other, in order to speed up disk access and improve performance.

Dry run

the process of executing the algorithm outside the machine, either in the programmer's head or using pencil and paper. Reasons to dry run include to identify the purpose of an algorithm, to ensure it is functioning correctly, and to identify any logic errors.

Fetch-decode-execute cycle

the sequence of steps carried out repeatedly by a CPU when executing a program.

File repair

the process of extracting as much reusable data from a corrupted file as possible.

Fragmented

parts of a file are scattered across a disk rather than being stored sequentially.

GUI

graphical user interface, with windows, icons, menus and pointers.

Hardware

the physical components of a computer system.

High-level language

a programming language that resembles human language and enables a programmer to write code that is independent of a particular CPU's architecture.

Integrated Development Environment (IDE)

a package that helps programmers to develop program code. It has a number of useful tools, including a source code editor and a debugger.

Interpreter

a translator that converts high-level language source code into machine code, one line at a time whilst the program is being executed.

Language-specific vulnerabilities

a known flaw in a programming language that can pose a threat to security.

Low-level language

a programming language that is closer to machine code than human language and requires detailed knowledge of a particular CPU's architecture.

Machine code

the binary codes representing each of the instructions in a CPU's instruction set.

Machine dependent

code that will only run on a computer with a particular architecture.

Main memory

a temporary store for data and program instructions.

Malware

software that has been designed to gain unauthorised access to a computer system in order to cause damage, disrupt its functioning or collect information without the users’ knowledge.

Multitasking

in an operating system, this enables several applications to be available at the same time.

Object code

the translated source code. The output from a compiler. Often this will be machine code, but might also be an intermediate code, which has to be further translated before it can be executed.

Operating system

a program that controls and manages the hardware and other software on a computer, and provides a user interface.

Patches

updates that are applied to existing software to correct errors, behaviours or security vulnerabilities.

Peripheral device

a hardware device such as a printer or a keyboard attached to a computer.

Pipelining

a way of improving the performance of the CPU. The stages of the fetch-decode-execute cycle are overlapped. While the CPU is executing one instruction, it is decoding a second and fetching a third one from memory.

RAM or random-access memory

a computer's main memory. Locations in RAM can be accessed in any order directly. The content of RAM is lost when the power is turned off.

Robust software

code that can handle unexpected actions without crashing or producing incorrect output.

Runtime error

an error that occurs while the program is running — the operation the computer is asked to do is impossible to execute. Runtime errors often cause a program to crash the computer or application.

Scheduling algorithm

used to allocate each process running on a computer a share of the CPU's time.

Signature

the fingerprint of a virus. It is a set of unique data, or bits of code, that allow it to be identified.

Software

the set of programs running on a computer which direct it to perform specific operations.

Source code

the text of the program that a programmer writes ina programming language. It needs to be translated into machine code in order to be executed by a computer.

Stored program concept

• both the program instructions to be executed and the data to be used are stored together in a computer's main memory.

Trace table

a technique used by programmers to track the changes to variables as a program is executed by a human. Each column represents a variable or output and each row represents a change in value of that variable.

Translator

a program that converts source code written in a high-level language into machine code.

User interface

the way in which the user interacts with the computer system.

Utility software

programs that add functionality to a computer or improve its performance in some way. These include backup and disk repair.

Version control

a way to keep track of changes to code so that programmers can go back and retrieve previous working programs.

Virus

a piece of malicious code that attaches itself to a legitimate program and is activated when the ‘host’ program is run.

WIMP

windows, icons, menus and pointers - the term used for operating systems like Microsoft Windows and macOS.