Exam unit

All revison notes needed for exam Unit for AS computing

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  • Created on: 08-06-09 20:15
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Chapter 1: Computer Hardware
HARDWARE = The physical components (electronic circuits) that make up
the computer.
SOFTWARE = The programs that run on the hardware.
PROCESSOR = The function of a processor is to fetch the next instruction,
decode the instruction and execute the decoded instruction. The processor
is sometimes referred to as the CPU.
SECONDARY STORAGE = Is the most common form of auxiliary storage.
Secondary storage is a long term, non-volatile storage medium (e.g. hard
drive) that contains the operating system and any other data of a permanent
RAM = Random Access Memory is a volatile type of memory meaning that it
loses it's contents when the computer is switched off. RAM is used to store
the currently running programs on the computer. Increasing the amount of
RAM in a computer will enable faster execution of programs.
ROM = Read Only Memory is anon-volatile type of memory meaning it's
contents are permanently etched into a memory chip. The BIOS and the
system clock is commonly stored in the ROM.
CACHE MEMORY = Is fats memory that acts as an intermediate between
the CPU and the main memory, storing the most frequently used instructions
and data.
DISK STORAGE = The most common form of auxiliary storage.
Chapter 2: Classification of Software
SYSTEMS SOFTWARE = Performs tasks needed to run the computer
APPLICATION SOFTWARE = Software designed to carry out some task
for the user that is primarily independent of computers e.g. writing a
made to do many different tasks.
specific task.
BESPOKE SOFTWARE = Software written to specification of a particular
organisation or customer.
OPERATING SYSTEM = The operating system is the software that
manages computer resources and provides users with an interface used to
access those resources.

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LIBRARY PROGRAM = Is part of library facilities of a computer used to
find lost files or restore corrupted files.
UTILITY PROGRAM = Is devised to perform operations on files or data.
PROGRAM LANGUAGE COMPILERS = A computer program that
translates text written in computer language into another computer
INTERPRETERS = A computer program that performs commands written in
programming language. Most important way a program can be run.…read more

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SAMPLING RATE = The frequency at which the samples are taken.
BIT-MAPPED GRAPHICS = When each pixel is represented by a binary
PIXEL = The smallest resolvable rectangular area of an image.
VECTOR GRAPHICS = Each graphic is stored using a mathematical formula
to define the shapes.
Chapter 6: Programming Concepts
1st Generation = Machine Code
2nd Generation = Assembly Code
3rd Generation = High level Language Code e.g.…read more

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ALGORITHM = A mathematical rule or procedure for solving a problem.
Chapter 9: Queues and Stacks
DATA STRUCTURE = Is a way of organising data, can be either static or
QUEUES = A first in first out data structure (FIFO). New items may be
added to the end of the queue only and removed from the front of the queue
STACKS = A last in first out data structure (LIFO).…read more

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BANDWIDTH = The range of frequencies that a medium can successfully
EVEN PARITY = When number of 1s come to an even number and is used by
integrity of data where the parity bit is re-calculated.
ASYNCHRONOUS DATA TRANSMISSION = One character at a time is
sent, with each character being preceded by a start bit and followed by
one or two stop bits.
HANDSHAKING = The exchange of signals between devices to establish
their readiness to send or receive data.…read more

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WAN = Wide Area Network connects computers and networks together
over a wide geographical area (e.g. national banks)
MODEM = A modulator demodulator converts analogue signals (telephone
lines) into digital signals (computer) and vice versa.
ISDN LINES = Integrated Services Digital Network is a network that is
capable of sending voice, video and computer data.
DATA COMPRESSION = Is used when frequently transmitting large
quantities of data therefore reducing the number of blocks transmitted.…read more

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Header and Footer
-Page numbering
-Find and replace text
-Print preview
DESKTOP PUBLISHING = Is an extension of word processor and used to
create documents such as flyers, newspapers, magazines and books.
-Easier control over page layout
-Better for very long documents (e.g.…read more

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TEXT FILE = A file containing characters organised on a line-by-line basis.
NON-TEXT FILE = Content of file cannot be displayed sensibly in a text
editor because it contains binary codes of nonprintable characters.
PRIMARY KEY = A unique field of a record used to identify the record.
FOREIGN KEY = A primary key in another table.
SECONDARY KEY = A field that may not be unique, but may be used
to locate a group of records.…read more

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1-Natural hazards such s fires, floods, hurricanes etc.
2-Deliberate corruption or destruction of data by malicious or terrorist
3-Illegal access to data by `hackers'
4-Accidental destruction of data by hardware failure or program or
operator error.
1-Vetting of prospective employees
2-Seperation of duties
3-No unauthorised access to secure areas
4-Use of passwords to gain access to secure areas
5-Appointing a security manager
6-Using special monitoring software
DATA ENCRYPTION = Prevents confidential data from being read by
unauthorised hackers.…read more


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