Chapter 4 - Software Flashcards
Types of software (hierarchy of software and hardware)
Application software
System software
Hardware
Examples of Application software (8)
Programs that allow users to do specific tasks
Data base - used to organise, analyse and manipulate data
Spreadsheet - organise and manipulate numericalk data
Word processor - used to manipulate text data
Control+measuring software - allows microprocessor to interface with sensors to measure physical quantities etc
Photo editing software - manipulate stored digital photographs
Video editing software - manipulate videos to produce new videos
Graphics manipulation software - allows bitmap and vector images (lines,curves and text) to be changed
Apps - applications, downloaded from appstore, banking, gaming etc
General features of application software (4)
Used to perform various applications on a computer
Allows a user to perform specific tasks using a computers resources
May be a single program (NotePad) or a suite of programs (microsoft office)
User can execute the software as they require
Utility programs offered by most computer systems (7)
Virus checkers
Defragmentation software
Disk contents analysis and repair
File compression and management
Back up software
Security
Screesavers
General features of system software (5)
Set of programs to manage the operation of computer hardware
Requires a platform on which other software cun run
Required to allow software to run without problems
Provides Human Command Interface (HCI)
Controls allocation and usage of hardware resources
WIMP
Windows Icons Mice and Pointing device
Set of software features and hardware devices designed to simplify computing operations for the user.
System software (5)
Programs that allow the hardware to run properly and allow the user to communicate with the computer
Compilers - translates programs written in HLL into machine code
Utilities - software designed to carry out specific tasks on the computer
Device drivers - software that enables 1+ hardware devices to comunicate with the OS
Operating Systems -
Linkers-takes 1+ object files produced by compiler and combines them into a single program to be run on the computer.
Common features of anti virus software (6)
Heuristic checking- checking software for behaviour that could indicate a virus
Must be kept up to date
Quarintine files/programs, auto deleting them or allowing the user to delete them
Full system scans done once a week to check for dormant viruses
Compares a possible virus against known data
Check software/files before they are run or loaded onto a computer
Quarantine
To isolate a file identified by anti virus software as having a virus
False positive
One of the drawbacks of anti-virus software, the software believes the file is infected but it isnt
Defragmentation software
Software that reorginises sectors on HDD by rearanging blocks of data so that they are contiguous, improving data access by reducing HDD read-write head movements
Back up utility
Creates a backing up schedule for files and only back up once changes have been made
Creates 3 versions of the file:
-Current - internal HDD/SDD
-Local-portable SDD
-Remote-Cloud storage
What microsoft windows offers using back up utilities (4)
Restore data, files or computer from the backup
Create a restore point (time machine-can restore computer to a previous state)
Options of where to save backup files
File history - you have to switch it on, takes snapshots and stores them allowing the user to choose a file version from the library created
What Mac OS offers using back up utilities
Time machine
Erases contents of selected drive and replaces it with contents from back up.
Need an external HDD or SDD connected via USB port to ensure it is effectively stored
Automatically backs up every hour, day and week
Security software(5)
Over arching utility that
protects network interfaces (use of firewalls)
overseas updating of software (does it come from a legit source?)
links into other utility software (virus checkers etc)
encrypts and decrypts to ensure intercepted data is useless without a key
manages control and user accounts using IP addresses and passwords
Types of system software (5)
Utility programs
Operating systems
Linkers
Compilers
Device drivers
Device drivers
Software that communicates with operating system and translates data into a format that can be understood by hardware peripheral devices to stop them from saying “device not recognised”.
Contain descriptors, collections of data about a device plugged into the USB port, can be Vendor ID OR Product ID or serial number. If the device plugged in has no serial number associated with it the OS will treat it as a new device
Screensavers
Programs that provide still or moving images on the computer monitor after periods of inactivity. Originally developed to protect the old Cathode Ray Tubes from phosphorus burn and is not neccessary on new OLED and LCD screens but serves as an extra layer of security as it logs you out after a period of inactivity.
Used during virus scans and distributed computing applications (allow apps to use computers resources when idle)
Operating system functions (9)
Multitasking
HCI - Human Computer Interface
Platform for running application software
Management of user accounts
Managing files
Managing peripherals and drivers
Memory management
Interrupt handling routines
Providing system Security
Operating systems
Enable computer systems to function correctly and allows users to communicate with computer systems by providing an enviroment in which applications can run as well as a useable interface between computers and humans. Disguises complexity of computer software eg. microsoft windows, Apple Mac OS, google android.
where do computers and phones store the operating system
Computers store it on HDD or SDD since they are large programs
Phones store it on SSD since they are to small to have an HDD
What happens to backups when the SSD or HDD is almost full
The oldest backups are deleted and replaced
CLI
Command line interface
Interface that allows communication with the computer by typing in commands using a keyboard
GUI
Graphical User interface
Interface that allows users to interact with computers usingicons to represent apps and tasks that a user can click on using a mouse or touch screen (WIMP + post WIMP )
Post WIMP
Modern touch screen that uses pinching, rotating and tapping to select icons.
Who would use CLI
Someone who needs direct communication with a computer to develop new software or look for and fix errors. Programmer, analyst, technician.
Who would use GUI
End user with limited knowledge on how computers work. Use computers to run software, play games and edit photos.
Advantages of CLI (4)
Allows for direct communication with computer
Not limited to predetermined options
Possible to alter computer figuration settings
Uses a small amount of computer memory
Disadvantages of CLI (3)
User has to memorise commands in order to carry out basic functions
Takes time to type in commands and there can be mistakes
Commands must be typed with specific spelling and format
Advantages of GUI
Much more user friendly
Simpler as all you have to do to launch an application is click on an icon
Dont have to memorise commands
Disadvantages of GUI (3)
Limited to icons on the screen
Uses more memory than CLI
Requires an operating system to function which uses up even more memory
Memory management
Software that manages the primary storage (RAM) and the moving of data from RAM to HDD/SSD
Keeps track of all memory locations
Carries out memory protection to ensure 2 competing applications dont store data in the same memory loaction as it could lead to lost data, incorrect results produced by the applications and the computer crashing
EEPROM
Electronically Erasable Programmable ROM
Boot up/bootstrap loader
Small program used to load other programs to correctly start up a computer system
Security management
Part of operating system that ensures integrity, confidentiality and accessability of data.
Features of security management (7)
Prevents illegal intrusion into the computer
Maintains users access rights
Sets up user accounts using passwords and user IDs on multi user devices to prevent access to “ptivate areas”
Communicates with the firewall to examine the traffic flow
Carries out OS updates when available
Ensures security software is up-to-date
Offers the ability to restore lost or corrupted data and to restore the system
Buffer
Memory area to temporarily store data
Hardware and peripheral management
Part of the operating system that controls all input and output devices and is made up of sub systems such as printing management
Features of hardware peripheral management (4)
Communicates with input and output devices using device drivers
Uses device drivers to translate data from a file into a format that the input anbd output devices can understand
Manages input and output data by controlling queues and buffers
Ensures that each hardware resource has a priority so that it can be used and released as required
Role of printer management when printing out a document(5)
Part of peripheral hardware management
- printer driver is located and loaded into memory
- data is sent to printer buffer ready for printing
- if the printer is busy or the printing job has low priority it is first sent to the printing queue (not buffer)
- sends various control command to the printer during the printing process
- handles error messages and interrupts from the printer
File management
Part of operating system that manages files in a computer
Main tasks of file management (5)
- file naming conventions (filename.docx)
- performing specific tasks (open, edit close etc.)
- maintain directory structures
- ensuring access control is maintained
- ensurimng memory allocation for files by reading it from the HDD/SSD and loading it into memory
Multitasking/multiprocessing
Function that allows comoputers to process more than 1 thing at a time
Risk of pre-emptive multi tasking
Low priority processes could be starved of resources
Pre-emptive multitasking (3)/what is done to ensure the processes dont clash
Resources allocated to each process for a specific amount of time
Process can be interuppted while its running
Each Process is given a priority to determine the resources allocated to it
Management of user accounts
Allows more than one individual to use a computer and stores each of their data separately in storage.
What management of user accounts allows(2)
Each user to customise their layout and other settings
Users can use separate files and folders to organise themselves
Administrator
Personal responsible for the upkeep and maintenace of a computer system that involes multi-user function. Have the power to restrict access, monitor and delete accounts etc.
What handles the start up of the computers motherboard and what it does
BIOS/firmware
Basic Input/Output System
It tells the computer where the storage device holding the operating system can be found, loads the neccessary parts and excecutes it
Firmware
Program that provides low-level control for devices
EEPROM
Electrically Erasable Programmable Read Only Memory
Where BIOS is stored
A flash memory chip meaning that its contents remain even when a computer is powered down. Also means that BIOS can be rewritten or deleted
Wheren are BIOS settings stored
CMOS chip
Complementary Metal Oxide Semi-conductor
Stored here as it is powered up at all times via a recharchable battery on the motherboard, meaning the settings would reset if the battery was removed or disconnected
What happens to BIOS when the CMOS is restarted
The BIOS settings will revert back to factory settings, but the same BIOS program will be accessed from EEPROM
Interrupt
A signal sent from a device or software to the microprocessor, causing it to temporarily stop what its doing to service the interrupt
What happens when multiple functions are running at the same time
Data is being rapidly passed in and out of memory
Interrupt causes (5)
A timing signal
Software errors (two processes trying to access the same memory location/ trying to divide by 0)
User interaction
Input/output devices process (printer requesting more data)
Hardware fault (paperjam in a printer)
What happens when an interrupt signal is recieved
The microproccessor either carries on with what it was doing or stops to service the interrupt based on the interrupt priority
Where are buffers used apart from printing
When downloading a movie from the internet to compensate for the difference between download speeds and data requirements of the receiving device. Data transmission rate of the movie file from the web server must be greater than the rate at which data is transmitted from the buffer to the media player or else it would constantly freeze
why are buffers so important
Without them the microproccessor would remain idle for a while, wasting its time while waiting for the document to print. Buffers allow the microproccessor to carry on with other tasks after uploading data to the printer
Explain how to print a document (refer to buffers) (7)
If there is no data sent to the printer the processor carries on with its tasks
If there is data, it is sent to the buffer from the computer memory
The buffer is emptied to the printer and the data is printed and the processor continues other tasks
If not all the data has been sent to the printer the buffer is emptied again
When the data is printed and the buffer is empty the processor recieves an interrupt signal
The signal requests more data to be sent to the printer
The current task is suspended to service the interrupt and the process starts again
Computer program
List of instructions that enable a computer to perform a specific task
High level languages advantages (4)
Enable a programmer to focus on the problem to be solved and requires no knowledge of the hardware + instruction set of the computer that will use the program. PORTABLE meaning they can be used on different computers. Jva, Pascal, Python, C++. Needs to be translated into machine code before it is executed
Easy writing and reading of code
Machine code
Binary programming language that can be loaded and executed without translation
ISR
Interrupt Service Routine
Software that handles interrupt requests and sends a request to the CPU for proccessing
Low Level language
Eg. Machine code and assembly language
Programming language dependant on computer hardware
why do programmers not write in machine code
Difficult to understand
Complicated to manage data manipulation and storage
What is machine code usually shown in
Hexadecimal
assembly languages
Form of low-level language that uses mnemonics and needs an assembler to be translated machine code before it is executed.
Why programmers write in assembluy language (4)
To write code that takes up less primary memory storage
To write make use of special machine instructions
To make use of special hardware
To write code that is executed quickly
Advantages of HLL(5)
Easier to read, write and understand
Quicker to write programs
Easier to maintain in use programs
Easier and quicker to debug programs
Independant type of computer being used
Disadvantages of HLL (3)
Takes longer to execute
Programs may be larger
May not be able to make use of special hardware
Advantages of LLL (4)
Can make use of special hardware
Includes special machine dependant instructions
Doesnt take up much space in primary memory
Writes code that quickly performs taks
Disadvantages of LLL (2)
Takes longer to write and debug programs
Programs are more difficult to understand
Types of translators
Compilers
Interpreters
Assembers
What translator/translators produce executable files of machine code
Compilers and assemblers
Main Difference between compilers, interpreters and assemblers
Compilers first translate HLL (Compiler) or LLL (assembler) into machine code before producing an executable file. Interpreters dont need an executable file as they execute the HLL program one statement at a time
Advantages of interpreters (2)
Easier and quicker to debug and test programs
Easier to edit programs during development
Disadvantages of interpreters
Programs cant be run without interpreters
Programs take longer to execute
Advantages of compiled programs(4)
Can be run without a compiler
Take up less memory
Shorter execution time
Easy to store
Disadvantages of compiled programs
Takes longer to read, write test and debug programs during development
IDE
Integrated Development Enviroment
software that consolidates basic tools required to write and test software to make a programmer’s journey effective and useful
Features of IDE (7)
Auto correction
Auto completion
Auto documentation and prettu printingh
Translator
Code editor
Runtime enviroment with a debugger
Error diagnostics
Code editor
Feature of IDE that allows a program to be edited without the need to use a separate text editor speeding up the development process
Translator
Feature of IDE
Can be a compiler and/or interpreter and enables the program to be executed. Interpreter used to develop the program and the compiler used to produce the final version
Run time enviroment with a debugger
Feature of IDE
Debugger is a program that runs under development and allows the programmer to single step through the problem/ set a breakpoint to stop the execution at a certain point in the code. Allows the programmer to see logic errors and if the program is being run as intended. Report window pops up evaluating variable content and expressions
Error diagnostics and autocorrection
Feature if IDE
Dynamic error checking finds possible errors as the code is being type and alerts the programmer and provides a suggestion allowing the code to be error freee before it is run
Auto completion
Feature of IDE
Offers sensible text promts with text completion for variable names and reserved words
Auto documenter and prettyprinting
Features of IDE
Auto documentor - explains function and purpose of programming code
Pretty printing - displays source code using different colours and formatting, making it easier to read and understand
Fffft
Tttf
System vs application software
System software provides the services that the computer requires (including OS and utility software)
Application software provides the services that the user requires
How hardware, firmware and an operating system are required to run applications software
Applications are run on the operating system which is run on the firmware which is run on the hardware
When would an interpreter vs compiler be used
Interpreter when developing a program, compiler to translate the final program
High level languages disadvantages (3)
Programs can be larger
Programs take longer to execute
Programs may not be able to make use of special hardware
Low-level language advantages (4)
Can write code that performs a task very quickly
Code doesn’t take up too much space in primary memory
Includes special machine-dependent instructions
Can make use of special hardware
Low-level language’s disadvantages (2)
Takes longer to write and debug programs
Programs are more difficult to understand
Operation of Compilers (2)
Translates while code before executing it (produces an executable file)
Provides error report for the whole code if errors are detected
Operation of an Interpreter (2)
Translates and executes the code line-by-line
Stops execution when an error is found
