Notesale: Turn your study into money

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CHAPTER 2 – SOFTWARE (UNIT 1: Digital Technology)
THE NAME OF THIS GCSE: DIGITAL TECHNOLOGY (MULTI-MEDIA)
HOW LONG IS THE TEST FOR UNIT 1: 1 HOUR
HOW MUCH IS THE PERCENTAGE WORTH FOR UNIT 1 OF THE OVERALL GCSE: 30%
Key Components of a Computer
HARDWARE: CPU [central processing unit - where most calculations take place], discs, mouse, printer
SYSTEM SOFTWARE: operating system, utilities
APPLICATION SOFTWARE: computer games, spreadsheets, word processors, databases, internet browsers
+ DISK – where information/data are stored permanently
+ MEMORY – where information/data are stored temporarily
(ex: words typed but not saved = stored temporarily)

Software
2 TYPES OF SOFTWARE– System Software, Application Software
 SYSTEM SOFTWARE: operating system, utility program
 APPLICATION SOFTWARE: bespoke, specialist, generic

System Software
The interface between computer hardware and user application programs
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 Enables the computer to operate its hardware and applications software
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questions:
1
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How much does it cost? Can you afford it?
3
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What are the minimum system requirements?
5
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What support is available for the users?
7
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LIST (2) FUNCTIONS HASON CAN EXPECT THE OPERATING SYSTEM TO PERFORM
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 Allocate internal memory (RAM) to programs and data currently being used
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 Error handling
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 Manage the transfer of data between your memory or working drive
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[Graphical User Interface = has menus and sub-menus, used by most people]
[Command Line Interface = these computers assume that the user does the correct thing straight away (ex:
deleting a file at once and not asking if the user is sure of it), used by experienced professional workers]

REAL-TIME PROCESSING [modes of processing]
In this, data is processed immediately after it is input
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 Used to avoid disaster
[ex: current position of aeroplane needs to be shown on the operator’s screen  Change in
position  immediate update of screen  correct information and avoids other aircraft]
Applications that use real-time processing:
 Airline/Concert Booking Systems
 Online Stock Control Systems
 Air Traffic Control Systems
QUESTION: WHY DO SOME SYSTEMS USE REAL-TIME PROCESSING?
The information in a system has to be processed immediately for update to prevent future issues
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(ex: if plane position not updated for 5 mins  issues)

BATCH PROCESSING [modes of processing]
1
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Inputs the data at an agreed time
3
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(from 1 billing period to the next)
- Customer account number
- Customer name
- Address details
- History of previous meter readings
Example: Electricity Billing System collects meter readings from houses to produce quarterly bills for
electricity usage
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‘time-sharing’ / ‘time-slicing’ system
Works by OS switching at high seed between the computers giving each one in turn a small amount
of processor time = ‘time slice’

Special facility provided by OS for multiprogramming:
MULTI-TASKING SYSTEM [modes of processing]



Having multiple (programs, processes, tasks, threads) running at the same time by 1 user
[when computer does more than one task simultaneously by the use of common processing
resource (ex: CPU and Memory)]
CPU works on one task only while other tasks waiting their turn (process/thread context switching)
[The illusion of parallelism is achieved when the CPU is reassigned to another task]

SYSTEM SOFTWARE - Utility Software
A program that carries out a specific task to assist the operating system
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o File broken down into a number of data blocks by OS before stored on a disc
 Each block stored in a free block space on a disc
 A number of free blocks which are spread across the disc will be available to store new
files as new files are saved and older files are deleted over time
 Single (large) file is broken up and stored in different parts of the disc if not enough
adjacent free block spaces for the blocks to be stored together
= DISC DEFRAGMENTATION
o Disc Defragmenter is used as the process of disc maintenance
= Rearrange the file data saved on disc = Speeds the time it takes to access files
 So the files are stored in blocks all together
 So the free blocks (free storage space) are together in the same part of disc
 Task Scheduling
o A utility that divides the processor time amongst a number of tasks
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 Normally installed on computers connected to the internet
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1
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Scan files stored on a computer comparing them to a known database of viruses
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Scan data entering a computer system comparing them to a known database of viruses
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Database of viruses updated regularly to detect any new viruses along with known viruses
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General-purpose (Genetic)
 Performs many different related tasks
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Specialist
 Performs a very specific type of task
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Tailor-made (Bespoke/Custom built)
 Specially developed software for specific purpose for a company
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