Software Flashcards
What is software
Software consists of programs, routines and procedures (with their associated documentation) that can be run on a computer system
Consists of programs (set of programs) that make the hardware function and also carry out tasks for the user
What are the 2 types of software and the types in it
System software
-Operating system
-Utility software
-Library programs
-Language translators
Application software
What is Application software and eg
Used to perform a specific job for a user that they would perform by other means
E.g. word proccing software to write a report, spreadsheet software to manage finances
What is system software
A computer system requires a layer of software that enables users to operate it without having to know the underlying processes that are going on inside all the time
It is software that helps users to use the computer and application programs such as providing the user interface and tools to manage the hardware
The systems software is provided by the manufacturer and enables a user to give a few simple instructions that the systems software translates into the millions of minor operations needed of the computer to function in a easy to use way
Software that is essential to the running of the computer is usually sold with the computer. Other systems software may be purchased separately to enable the computer to be used for particular types of tasks
Classification of system software
Necessary to run the computer- Operating system software
Provide other useful functions- Utility programs
Provides for frequently used tasks-Library programs
Enables software to be produced and maintained- Language translators such as compilers, interpreters and assemblers
What is the operating system
It is a suite of programs that controls the entire operation of a computer.
It is software designed for a particular hardware which manages other programs’ access to the hardware
It is normally provided through the supplier and manages the internal functions of a computer, such as memory management, multi-user, handling what has been typed in, displaying data on the screen and loading from and saving to backing storage
OS sits between the hardware and the programs. It hides all the complexities of the hardware form the user
The OS is software that
Manages a hardware device
Manages users’ access to the I/O devices, including files on secondary storage
Provides the user interface
Shares the computing resources such a CPU as memory between processes
Name the functions of the OS
Hardware management
File management
Shares access to the hardware among the different programs/tasks that are running
Multi-user/multi-access
Resource management
Provide user interface
Managing security
Hardware management in the OS
Involves all input and output peripheral devices
The functions of hardware management include
-Communicating with all input and output devices using device drivers
-Translating data from a file (defined by the OS) into a format that the input/output device can understand using device drivers
Applications written for particular OS will work on any hardware but might not work on a different OS
File management in the OS
Managing files- defining the file naming conventions which can be used- filename.extension (.txt, .xls, .docx etc. )
Performing specific tasks, such as create, open, close, delete, rename, copy, move
Maintaining the directory structure
OS shares access to the hardware among the different tasks that are running
Multitasking- method of organising computer use that allows several different tasks or applications to be available at the same time. Modern personal computer OS allow users to have several tasks to apparently run at the same time, with the user switching between applications or tasks
Multi-user/Multi-access in the OS
Several users can be sharing the hardware
allows several users to apparently have individual control at the same time
This needs sharing of hardware resources such as CPU and RAM
When several applications are open, they cannot really run at the same time
The OS uses a method called scheduling to allow each program to use the CPU for a given time before switching to the next program
One method of implementing a multi-access system is by allocating a period of time to each user, called time-sharing
Users should provide authentication to login
Ram is shared by a method called paging
Paging is an algorithm the OS uses to move programs from RAM to disk and back again when main memory is full. This is called paging, swapping or virtual memory
Paging is the organisation of memory into fixed size units, called pages. The immediate access store (RAM) is organised as a number of physical pages. The logical pages used by the CPU can be assigned, by the memory management unit, to any page in the physical memory. A form of virtual memory can be used with less frequently used pages being stored on disk, but when required they are reloaded into the IAS as a complete page
Resource management in the OS
Each task that is running is calling a process and this includes application programs
These processes are running one at a time, being given their share of CPU time by the scheduler.
The processes run alongside each other, but not really at the same time (concurrently)
An OS that allows processes to run concurrently is called a multi-tasking OS
Providing user interface in the OS
To provide communication between the user and the computer
Graphical user interface (GUI) based on WIMP (windows, icon, menus and pointer)
Command-line interface (CLI)
the choice of user interface depends on the application a computer is expected to run
An embedded system might not have a OS, therefore it does not have a user interface
A computer acting as a web server might only need a CLI because it is intended only to be accessed by technicians
A computer used for video editing will need a GUI
Managing security in the OS
Checking for authentication
Checking for access rights- authority to use certain facilities of the computer system is bases on the duties and the responsibilities of the user
Utility software
Tools
Software that performs some specific tasks in the operation of the computer (does useful jobs for the user, such as file management)
It is a type of systems software, because it makes the operation on a computer easier, rather than doing a productive task
Some utility programs are supplied as part of the OS, but others can be bought from other software suppliers
Utility programs might be used to back up files, test memory, analyze disk space, manage power usage, compress data and schedule tasks
Utility software is not essential to the OS and it is not application software
What areas can Utility software be separated into
Basic tools
File management
Security
Basic tools in utility software
Usually included as part of the OS
A simple text editor (e.g. notepad or nano)
Calculator
Command prompt
Hex editor
Software for accessibility such as for producing large print
File management tools in Utility software
Software to keep data secure by making a back up copy of files in another location
Programs to recover files that have been deleted
Repair files that might have been damaged or have errors
Converting files between different formats- useful in multimedia files where there are large number of common formats
Defragmenter- is a utility that moves file clusters on a disk so they are closer to each other in order to speed up disk access
Compress files- to save storage space, to reduce the downloading and uploading time, reduce size of email attachments
Security tools in Utility software
Anti-malware software
Anti-virus software
Virus is a software that is designed to make and distribute copies of itself usually for malicious purposes
Anti-spyware software
Spyware- software seeks to record secretly the user’s actions on the computer- actions that may include typing passwords or other personal details over what the user believes to be a secure connection. It is installed secretly on a computer to record private information as the user enters it
Firewall- Computer application used in a network to prevent external users gaining unauthorized access to a computer system. A firewall may be software running in the main computer or a separate computer physically located between the system and the external access. It limits the data and instructions that can be received from or sent to external users
Simulation and modelling
Abstraction- hiding complexity, only exposing the key features of a situation and leaving out the details
Computer science allows people to do experiments that cannot be done in the real world such as
Increase the average temperature of the Earth to see what happens to the weather
“what if?” question- running a computer model with a given set of inputs to see what the model produces as a an output or prediction
e.g. what if the bridge was twice as long
Computer modelling enables experts to ask ‘what if’ questions without affecting the real world
Computer models are very useful by contain assumptions and simplification, so it is not possible to rely completely on their results
Problems with simulation and modelling
The model or simulation contains assumptions. It is not reality, so the answers might not be right
The real world is far too complicated to allow for every possible factor in the model. It is necessary to use abstraction to simplify it. This further reduces the chance that it will produce a completely right answer
Examples of computer models
Flight simulator allows pilots to fly endangering their lives or the lives of passengers
The atmospheric models used to forecast the weather
Models used for earthquake prediction. Models like these have to use information form past examples and probability to come up with their best guesses to what might happen and when
Common techniques used in such models are
Heuristic- a type of algorithm capable of finding a solution to a problem quickly and easily. This is done through trial and error and educated guesswork to cut corners and remove less likely alternatives. These algorithms do not always find the best solutions, but they will usually find one that works
Monte Carlo method- carrying out statistical analysis of several random samples to get approximate solutions to a problem. The larger the number of samples used, the more accurate the result is likely to be
Neural networks- process information in a similar way to human brains and learn and adapt over time. This makes them useful tools for recognizing faces, identifying illnesses and quality control
