CHAPTER 2 HARDWARE

AND SOFTWARE

Cambridge International AS and ALevel IT

AS Level IT Chapter 2 - Hardware and
Software Flashcards | Quizlet 1
HARDWARE
Hardware is categorised into input, output and storage
devices.

● Input devices allow data to be sent to a computer

(e.g.keyboard)
● Output devices allow the communication of
data/information from a computer(e.g. monitor).
● Storage devices store data on to a storage medium
so that it can be used at a later time.

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HARDWARE

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CENTRAL PROCESSINGUNIT

● The ALU performs calculations and

logical operations.

● The CU runs the fetch - execute

cycle which fetches instructions
from memory and executes them.

● Input data is taken from input

devices (such as a keyboard) or
storage and processed by the CPU,
which produces output data that can
be stored or sent to an output device
(such as a monitor).

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CENTRAL PROCESSINGUNIT

● CPUs usually consist of multiple cores.

● Each core is a separate processor, so a
quad-core CPU has four processors.

● Processors are measured by the number of

instructions they can process per
second(hertz).

● A 3GHz (gigahertz) processor can process

up to 3 billion instructions per second.

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 SYSTEM SOFTWARE

● Programs that are designed to maintain or operate the computer

system are known as system software.

 The software that operates the computer hardware is known

as the operating system.

 Programs that are used to maintain a computer system

(e.g. anti-malware software) are known as utility software.

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OPERATING SYSTEMS

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 1- OPERATING SYSTEMS
An operating system manages hardware by carrying out tasks such as:
● Allocating memory to software
● Sending data and instructions to output devices
● Responding to input devices such as when a key is pressed
● Opening and closing files on storage devices
● Giving each running task, a fair share of processor time sending error messages or
status messages to applications or users

● Dealing with user logons and security.

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 TASK
●

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 2- DEVICE DRIVERS
● While the operating system can manage
the general instructions to deal with
hardware such as displaying graphics on a
screen, it requires the use of device drivers
to deal with specific makes and models of
hardware.

● A device driver is the software that comes

with an external hardware component and
sends customized instructions to that
specific component.
printer
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 2- DEVICE DRIVERS
● By using common device drivers, software
applications are able to issue generic
commands such as ‘print’ to the
operating system without having to
know the different instructions required
for every different make and model of
external hardware components.

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 3 - Translators

i - COMPILERS
Exe file
Object file

● A compiler translates a program written in a high-level programming language in

to machine code which a computer can understand.

● The file containing the machine code is known as an executable file because it
can be executed by the processor.

● It can also be referred to as the object file. The original high-level

programming language file is known as the source file.
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 Object file - Exe file

i - COMPILERS
● When a program is compiled, the whole
source code is translated into the executable
file at once and can then be distributed to
resellers, customers and individual computers.

● As it is in an executable format, it can only run on operating systems for which the
compiler has translated it.

● For example, programs that have been compiled for Windows will not work on Linux
unless they are compiled again for Linux. The same situation exists with mobile phone and
tablet operating systems.

● If there are errors it will enlist all at ones, then need correction and recompilation of
whole code that is why DEBUGGING is slower in working

● Compilation is faster.
 i - COMPILERS
✘ Compilation process includes three stages
✗ Lexical analysis
✗ Syntax analysis
✗ Code generation
1-Lexical analysis
- White spaces and comment are removed from code.
- Rest code is divided into token.
- Token ,in fact represent “Key word”, constant, identifier, string
number, operator and punctuation mark.
 i - COMPILERS
2-Syntax analysis
 During syntax analysis ,syntax is verified.
 Each token is analyzed.
 After that a dictionary is created for all variables, their data types
and values.
3-Code generation
✘ After this source code is converted to machine code.
✘ This machine code is dependent on the OS where its compiled
 ii - INTERPRETERS

● Interpreters also translate a program written in a high level programming

language into machine code, but use a different method, instead of translating
the whole source code at once, it is translated one line at a time.

● This can be less efficient than a compiler because it takes time to do the
translating as the program is being executed and also because statements
within programming loops (e.g. FOR, REPEAT, WHILE) have to be analysed
eachtime round.(Compilation is slow)

● It removes error line by line so DBUGGING is faster.

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 ii - INTERPRETERS
● Interpreters are often used to translate
macros or application-based script languages
and object oriented languages (e.g.
Visual Basic and Java for Applications),
which can be particularly useful when a
document needs to be opened on a variety
of operating systems.(Produced an
intermediary code)

● Interpreters are also used when testing

programs so that parts of the program can be
executed without having to compile the
whole program. 104
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DIFFERENCE BETWEEN COMPILER &
INTERPRETER

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DIFFERENCE BETWEEN COMPILER &
INTERPRETER

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3- LINKERS

● Computer programs often consist of several modules (parts) of programming

code.

● Each module carries out a specified task with in the program.

● Each module will have been compiled into a separate object file.

● The function of a linker(also known as a link editor)is to combine the object files
together to form a single executable file. 108
 3-LINKERS
● In addition to the modules used, the program may make reference to a common
library.

● A common library contains code for common tasks that can be used in more than
one program, such as mathematical functions, memory management, progress
bars /output. The linker is able to link modules from a library file into the
executable file.

● Not all modules are always needed and a linker is able to select which modules
will be part of the executable file.

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3-LINKERS

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UTILITY SOFTWARE

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 4- UTILITIES
● Utilities are part of system software.They are designed to
perform functions which maintain the computer system.
These utilities perform different functions likes
● Memory Management
● Disk formatting
● Deletion of Files
● e.t.c

www.computerhope.com/jargon/u/utility.htm
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 i-ANTI-VIRUS
● Anti-virus software is sometimes referred to as anti-malware software as it
deals with other threats such as adware and spyware as well as viruses.
● It has two main functions.The first is an anti-virus monitor that is
continually monitoring the system for viruses and malware.
● If the anti-virus monitor detects any unusual behavior or tell-tale signs of viruses
or malware then it will prevent them from being executed so they cannot cause
damage to files or programs.
● The second function is to check for viruses or malware that may already be
on a system.This is usually known as scanning the system.

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i- Anti Virus
• Protection from Malware
• Keep up to date so combat latest Malwares
• Anti virus can remove and quarantine malwares.
• Different scanning options
• Facility to schedule scan
Method to detect virus
• Signature based detection
 Only able to detect old.
• Heuristic based detection(reverse engineering)
 Decomposed to and matched with DB
 Specific percentage of virus code found then declare as virus
 Drawback false positive can be there.
• Behavioral based Malware detection Advantages and Disadvantages
 Sending large email Anti Virus program
 Altering files www.hitechwhizz.com/2020/03/6-advantages-and-
disadvantages-drawbacks-benefits-of-antivirus-
 Sandbox execution software.html
 BACKUP
● Backup utilities create a second copy of data and
programs that are in a remote storage.
Manual/Automatic Backup
● A backup utility can be executed by the user, in which
case the backup takes place when the user ask it to, or it
can be scheduled to execute at a predetermined time
so that the backup takes place automatically.
● The user is usually able to select which folders and files
will be backed up and can usually decide where the
backup will be stored.
● Cloud backup ,baking up devices(CDRW, CDROM,Tape
Disk)
DATA COMPRESSION

● Data compression utilities will reduce the original

size of files so that they use up less storage space.
● This can be achieved on a file-by-file basis or for a
set of files or even a set of folders.
● It will be slower to open the compressed file, but as
it is smaller it will use up less storage and can be
transferred from one location to another more
quickly.

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DISC DEFRAGMENTATION

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DISC DEFRAGMENTATION

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 DISC DEFRAGMENTATION
● Track, Sector and cylinder
● As a hard disc gets used, files are kept together in storage on the same cylinder or
adjacent cylinders.
● As files grow in size, they use up more space on the disc and this may no longer be
on the same or adjacent cylinder.
● The problem with this is that when opening the file, the access arm of the hard
disc drive has to keep moving to different locations which makes opening the file
a slow process.
● When files are deleted, gaps are left on the disc. When all the cylinders have been
used, the only space to store files is within the gaps. If the gaps are not big enough,
then files have to be split across gaps, meaning that they become defragmented
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DISC DEFRAGMENTATION
●

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 DISC DEFRAGMENTATION
● A defragmentation utility will reorganise all the files so that each file is contiguous
(kept together).
● It will do this by moving fragmented parts of files and small files to free space on
the disc and creating space on whole cylinders or adjacent cylinders.
● It will then move the defragmented files to a place where the whole file is kept
together.
● This can significantly improve the performance of a computer system, especially if
program files have become fragmented and can be defragmented.

● https://www.youtube.com/watch?v=AtRIOUZuI2c
● https://youtu.be/2QmgbDKuhx8 37
 FORMATTING
● When a disc is prepared for first time use, it needs to be formatted.
● Formatting is the process of organizing the tracks on the disc into sectors.
Each sector is where data will be stored.
● A used disc can also be formatted, in which case all data will be lost and the tracks
prepared again as if the disc was being used for the first time.

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 FILE COPYING
● Files can be copied using features within an operating system’s own interface.
However, this can be slow and options are limited.
● File-copying utilities enable users to have more control over which files are
copied and how they are copied.
● For example, a user may only want to copy word processing documents that are
within a series of folders and they may want all the files to be copied to a single
folder on the destination storage.
● It is also possible to synchronize files across multiple storage locations or even
multiple computer systems, so that when a change is made to a file in one
location, it will then be updated in all other locations. 172
 DELETING
● Some files become locked by an operating system and it becomes almost
impossible to delete them.

● Deleting utilities can overcome this problem by deleting locked files and folders.
● When files are deleted using normal deletion methods, the data is still on the disc
although the user can’t see it.
● Therefore another function of deleting utilities is being able to delete files
permanently so that they cannot be restored or accessed.
● Some deletion utilities will remove temporary files that are no longer needed by
the computer system, or files that are no longer used but haven’t been deleted

when a program has been uninstalled or a user profile removed. 173

Past Paper QUESTIONS

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Past Paper QUESTIONS

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QUESTIONS

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CUSTOM-WRITTEN VS OFF-THE_SHELF SOFTWARE

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 CUSTOM-WRITTEN VS OFF-THE_SHELF
SOFTWARE(with respect to development)

● When a client requires a software solution that will carry out a specific
purpose that is unique to their organization, they will ask for the software to be
written for them. This is known as custom-written software because it is
customized to the needs of the client and will meet the requirements of the
client.

● When software already exists and is purchased online or from a shop, it is known
as off-the-shelf software. The software will have been written for a general
purpose that is likely to be useful to a large market. Anybody can purchase the
software for a specified price.(e.g adobe ,MS Office and SAP for accounting)
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CUSTOM-WRITTEN VS OFF-THE_SHELF
SOFTWARE

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CUSTOM-WRITTEN VS OFF-THE_SHELF
SOFTWARE

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QUESTIONS

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Proprietary software (With respect to ownership)
• Software owned by a single person or organization and sell under a license .
• Only exe file is provided while source code remain with owner
• Different type of license are available

 Freeware (can be used free of charges)

 Share ware (Same as freeware but active for a specific time then whole
or few features are not available)
 Single user
 Multi user

Example MS office

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 OPEN Source Software

• Often available as free software provided along the source

code.

• User can change source code and redistribute.

• But it is not compulsory in each case ,that is in many cases

source code will be provided for installation, customization and
redistribution on payment.
Like Mozila Firefox and open office
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 DIFFERENT TYPES OF USER
INTERFACE
● An interface is the boundary between two
systems.

● A user interface is the boundary between the

user and the computer system.

● A user interface represents the communication

between a user and the computer system.

● This communication can take many forms.

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 COMMAND LINE
INTERFACE
● A command line interface (CLI) allows a user to enter text commands to which the
computer system will respond.

● The computer system will respond by producing results in a text format.

● CLIs use very little memory so they are useful in old systems or for maintenance
of very small systems/devices (e.g.engine management systems).
● They are also useful for technical users who need to carry out complex
operations which cannot be performed using more user-friendly interfaces.
● However, CLIs can be difficult to learn and use because users have to learn
and remember all the commands, and errors are easily made when entering
those commands.
 DOS
COMMANDS

● DATE
● TIME
● DIR
● CLS
 GRAPHICAL USER
INTERFACE (GUI)

● The most common type of interface that we use is a graphical

user interface (GUI).
● GUIs are found on desktop computers, tablet computers, mobile
phones, televisions, set-top boxes, photocopiers and some in-car
entertainment systems.

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 GRAPHICAL USER
INTERFACE (GUI)

GUIs can include some or all of the

elements

The acronym WIMP is commonly

used to remember these elements.

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 GRAPHICAL USER
INTERFACE (GUI)
● Complex GUIs require a lot of memory to operate, but simpler GUIs can
be used where memory is limited.
● Although CLIs don’t require much memory, simple GUIs can be used
instead of a CLI in small systems such as embedded systems.
● It is common place to find simple web-based GUIs for the maintenance of
devices such as routers, switches and printers.
● GUIs are intuitive to use which means they are easy to learn because
commands are represented by pictures and menus provide options that can
be selected.
However, CLI can be restrictive for some technical users who need to
carry out unusual tasks. 153
 Important Features of User
Interface Design
● Colour -Text must be legible.This means using a light font on a dark background or a
dark font on a light background.

● Layout - Careful consideration should be given to the layout of information, icons and
inputs on a screen. Similar information, icons or inputs should be grouped together.

● Font size- The standard size of font for reading is 11 or 12 points which is legible
for most users.

● Quality of information - If too much information is provided to a user, then this can
cause information overload and may mean that much of it is ignored.

● Controls- Controls are used on form. 156

CONTROLS

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CONTROLS

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CONTROLS

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Badly Designed Input
Screen

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DIALOGUE INTERFACE

● A dialogue interface refers to using the spoken word to communicate with a

computer system.

● A user can give commands using their voice and the computer system can
respond by carrying out an action or with further information using a
synthesized voice.

● Dialogue interfaces are very popular with mobile devices, including mobile
phones and in-car entertainment systems.

● The main problem with this type of interface is the computer system’s ability to
recognize the spoken word. 154
 GESTURE - BASED
INTERFACE

● Gesture-based interfaces will recognise human motion.

● This could include tracking eyes and lips, identifying hand signals or
monitoring whole body movement.

● There are many applications of gesture-based interfaces, including

gaming, which have led to the development of other gesture-based
interfaces.

● Gestures can be an essential form of interaction for some disabled users who
cannot use conventional input devices.
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Thank You