Computer systems Vocabulary

Hardware

The physical/electronic components of the computer system.

Software

Program/code/instructions executed by the hardware. Truth table A representation of the output of a logical expression or circuit for all possible combinations of input variables.

Logic gate

An electronic component that takes one or more binary inputs and performs a basic logical operation (such as AND, OR and NOT) to produce a single binary output.

System software

System software is software that manages the computer system resources and acts as a platform to run application software.

Application software

Application software is software that performs end user tasks. Tasks that the user may wish to complete even without a computer (e.g. write a letter).

Utility software

Utility software is software that can help maintain a system. Examples include:
• backup software
• encryption software
• compression software.

Operating system (OS)

The role of an operating system is to hide the complexities of the hardware from the user. The operating system handles:
• resource management (processor(s), memory, input/output (I/O) devices)
• applications
• security.

Low level language

A low level language is one that is closer to the hardware and the computer's instruction set. Machine code and assembly language are examples of low level languages.

Machine code

Machine code is another name for the actual binary instructions that can be executed by a processor and is specific to a processor or family of processors.

Assembly language

Assembly language uses mnemonics that represent machine code instructions. Assembly language needs translating (assembling) before it can be run.

High level language

A type of language that is more abstracted from the hardware of the computer and in which instructions are more powerful than in a low level language.
HLLs use English(like keywords.)
HLLs support structured statements (such as iteration/selection.
HLLs support use of local variables and parameters.)

Program translator

A processor can only execute machine code instructions. So anything else (assembly language, HLL code) needs to be translated first into machine code before it can be run. Assemblers, interpreters and compilers are examples of translators.

Interpreter

An interpreter analyses the source code line by line. An interpreter will run the source code up to the first error. Interpreted code will execute more slowly than executing the code produced by a compiler. An interpreter always needs a copy of the source code at runtime. Interpreted code is more portable.

Compiler

A compiler produces object code from the source code. A compiler translates the whole source code at once. A compiler will not produce an executable file (will not compile) if an error is encountered. Compiled code can only be executed on a machine with the same instruction set. Once compiled, the object code (executable) can be executed without the need to have the compiler.

Assembler

An assembler translates assembly language into machine code.

Central Processing Unit (CPU)

The primary component responsible for processing data and executing instructions.

Arithmetic logic unit

A part of the processor where arithmetic and logical operations are performed.

Control unit

A part of the processor which
• decodes instructions
• coordinates/directs the execution of instructions
• sends control signals to other components.

Clock

Synchronises operations of the computer by sending regular timing signals to the processor.

Register

A memory location on a processor that can be accessed quickly. A register can hold data used when executing an instruction and the result of executing an instruction.

Bus

A bus is a series of lines (wires) that transfers data, instructions or memory addresses between components inside a computer.

Clock speed

The clock sends out regular pulses to coordinate the components of the computer. The frequency of these pulses Is known as the clock speed and measured in hertz, where 1 hertz = 1 pulse per second.

Core

A processing unit within a processor is known as a core. Each core can fetch, decode and execute instructions independently of the other cores.

Cache

Cache is a small area of fast memory built into a modern processor. Cache holds frequently used instructions and data that the processor is likely to reuse.

Volatile/non

volatile

RAM Random Access Memory

Main memory is considered to be any form of memory that is directly accessible by the CPU (except for cache and registers). Random Access Memory is volatile main memory. It is used to hold currently running programs and associated data. It can be read from and written to. Its contents are lost when power is removed.

ROM Read Only Memory

Read Only Memory is non volatile main memory. It is used to hold instructions that are needed for the computer to run especially when the computer is turned on. It can be read from but not written to. Its contents are kept when power is removed.

Secondary storage

Secondary storage is considered to be any non

Solid state

Solid state devices use non volatile memory to store data. They have fast data access and write speeds and are durable as they do not have any moving parts.

Magnetic

Magnetic devices such as hard disk drives have a spinning disk and use magnetic fields to represent 0s and 1s.

Cloud storage

Storing data at a remote location, using magnetic and/or solid state storage, and allowing online access is known as cloud storage. Access to cloud storage is made via the Internet.

Embedded system

An embedded system is a computer system built into a larger device. An example of an embedded system is the control system for a microwave or a washing machine