64 terms

Computer Science Computer Organisation (***)

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address bus
Pathway from memory to processing unit that carries the address in memory to and from which data is transferred. See the definitions for "bus" and "data bus".
arithmetic and logic unit (ALU)
A part of the computer that performs arithmetic operations, logic operations and related operations.
ASCII: American Standard Code for Information Interchange
The primary encoding character set used in computers for textual data transfer between applications. The set uses eight bits for each character code, one of these bits being a check bit to verify the seven bits needed to represent one character. ASCII supports most European alphabets. Unicode supports most known alphabets and is increasingly used in data transfer. See also the definition for "Unicode".
B
Byte.
backup (file)
A second copy of a file, to be used in the event of the original file being corrupted. See also the definition for "unbalanced tree".
bar code
A pattern of vertical lines distinguished from each other by width. It can be read by a bar code reader to provide data to a computer.
bar code reader
An optical reader that can read bar codes. In a decimal system the base is 10, in a hexadecimal system the base is 16, and in a binary system the base is 2.
bit (b)
Binary digit. The smallest unit of information for data storage and transmission. Each bit is considered to be either a "0" or a "1".
Bus
The pathway used for sending signals between internal components of a computer. Components can share the same bus but cannot transmit simultaneously.
Cache
Part of the main store that is between main memory and the processor. It holds a copy of data and instructions that are likely to be used next by the processor and is hence faster than main memory. See also the definition for "disk cache".
character set
A finite set of different characters that is complete for a given purpose, for example, the 128 ASCII characters.
computer architecture
The logical structure and functional characteristics of a computer, including the interrelationships among its hardware and software components.
database management system (DBMS)
A computer based system for defining, creating, manipulating, controlling, managing and using databases.
data bus
The pathway between the memory or peripheral and processing unit that carries data for processing or data that has been processed. See also definitions for "bus" and "address bus". All redundancy in the data is removed to reduce the storage needed or to speed up transfer. The data can be uncompressed back to its original state.
defragmentation software
An application that reads file segments from non-contiguous sections of a storage device and then writes the files to the same device in such a way that each file segment is contiguous.
digital data
Discrete data.
disk cache
RAM set aside to speed up access to a hard drive. This may be part of the disk itself or may be incorporated in cache memory.
encryption
In computer security, the process of transforming data into an unintelligible form in such a way that the original data cannot be easily obtained except by using a decryption process.
file manager
An application software that can access, create, modify, store and retrieve files. All such records in a file have the same length. See also the definition for "variable-length records".
graphics tablet (graphics pad)
An input device on which the user writes or designs. The image is reproduced on the screen.
JPEG (joint photographic expert group)
A recognized standard of compression of graphics files that has some loss.
memory address register (MAR)
Holds the address in memory of the instruction at present being executed. It is particularly important in multitasking systems where applications might otherwise cause conflicts, and for implementing virtual machines and virtual memory.
Microprocessor
An integrated circuit incorporating the main components of a central processor. These circuits are used for microcomputers and small devices controlled by computer.
Modem
An abbreviation for "modulator/demodulator": a piece of electronic equipment that converts digital signals from a computer into audio signals that are transmitted over telephone lines, and converts them back again.
Multitasking
A mode of operation that provides for concurrent performance, or interleaved execution, of two or more tasks.
OCR Optical character recognition (reader)
Refers to the use of devices and software to "read" characters and translate them into ASCII characters for later processing. Applications of OCR include the scanning of printed documents to convert the text into digital ASCII text that can then be edited in word processors.
operating system (OS)
It is the core of computer system software. It manages computer resources, such as memory, and input/output devices, and provides an interface through which a human can interact with the computer. It allows an application program to interact with system resources.
Software that controls the execution of programs and that may provide services such as resource allocation, scheduling, input/output control, and data management.
peripheral device
Any device that can communicate with a particular computer, for example: input/output units, auxiliary storage, printers. Used in dynamic data structures to move from item to item.
pointing device
An instrument, such as a mouse, trackball or joystick, used to move an icon (sometimes in the form of an arrow) on the screen.
primary memory
The part of the memory where the data and programs that are in use at the time are stored.
robustness
A term used to describe the ability of a program to resist crashing due to incorrect input or incorrect intermediate results.
search engine
A program that searches a large database to find matching items. The most common use of a search engine is to find Internet addresses based on given key words.
secondary memory
A type of memory that allows a user to store data and programs for as long as desired, in, for example, a hard disk drive. The point at which the sector intersects with a track is used to reference the location.
sensor
A device that detects measurable elements of a physical process for transfer to a computer.
speech recognition (voice recognition)
A process of comparing spoken words with those stored in the system.
Unicode
A standardized 16-bit character set that represents the character sets of most major languages in the world. See also the definition for "ASCII".
utility
A program designed to perform an everyday task such as copying data from one storage device to another.
virtual memory
The use of secondary memory as if it were primary memory.
magnetic ink character recognition (MICR)
The identification of characters through the use of magnetic ink.
single-tasking
A mode of operation that allows only one program to be in use at any time.
single user system
A system that only allows one user at a time.
accumulator
A storage register in the ALU that holds data temporarily while the data is processed and before it is transferred to memory.
data bus
The pathway between the memory or peripheral and processing unit that carries data for processing or data that has been processed. See also definitions for "bus" and "address bus".
Interrupt
A suspension of a process, such as the execution of a computer program caused by an external event, performed in such a way that the process can be resumed.
memory address register (MAR)
Holds the address in memory of the instruction at present being executed.
memory manager
A program that is usually part of the operating system that controls the allocation of memory to various applications. It is particularly important in multi-tasking systems where applications might otherwise cause conflicts, and for implementing virtual machines and virtual memory.
multi-processing
The simultaneous execution of two or more computer programs or sequences of instructions by a computer (parallel processing).
operating system (OS)
Software that controls the execution of programs and that may provide services such as resource allocation, scheduling, input/output control, and data management.
program counter
A register that holds the address of the next instruction to be fetched in the fetch execute cycle.
register
A part of internal storage that has a specified storage capacity and is usually intended for a specific purpose.
sector
The smallest accessible storage unit on a disk. The point at which the sector intersects with a track is used to reference the location.
serial interface
An interface through which a computer transmits or receives data, one bit at a time. See also the definition for "parallel interface".
verification (data input)
A method of ensuring that the data in the computer system is the same as the original source data. This may be done by double entry.
von Neumann Architecture
The computer design built upon the principle that data and instructions to manipulate data were logically the same and could be stored in the same place. Another major characteristic is that the units that process information are separate from the units that store information.
memory
A collection of cells, each with a unique physical address. Its addressability varies from one machine to another.
input device
A device through which data and programs from the outside world are entered into the computer. Modern examples include: keyboards, mice, cameras (also known as, simply, webcams), and scanning devices.
output device
A device through which results stored in the computer memory are made available to the outside world. Examples include printers and screen monitors.
Fetch, Decode, Execute
The process includes four steps: fetch the next instruction, decode the instruction, execute the instruction.
RAM
Memory in which each cell (usually a byte) can be directly accessed. Inherent in the idea of being able to access each location is the ability to change the contents of each location. That is, storing something else into that place can change the bit pattern in each cell
ROM
Memory which contents are permanent and cannot be altered by a second operation. Placing the bit pattern in it is called burning. The bit pattern is burnt either at the time the it is manufactured or at the time the computer parts are assembled.
auxiliary storage devices
Secondary memory e.g. magnetic tape, magnetic disks,CDs and DVDs,flash drives, external hard drives
application software
Software written to address specific needs e.g. word processing programs, games, inventory control systems, automobile diagnostic programs, and missile guidance programs.
system software
Software that manages a computer system at a more fundamental level. It provides the tools and an environment in which application software can be created and run. System software often interacts directly with the hardware and provides more functionality than the hardware does itself.
partition
When referring to a computer hard drive, it is a section of the hard drive that is separated from other segments, allowing e.g. multiple operating systems to run on the same device.
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