Computers π» | Software and Interrupts | 4.1 Flashcards
Define software
Code stored in the computerβs memory that is executed when it is run.
What are the two kinds of software?
System software and application software
What is the purpose of system software?
System software provides the services that the computer requires, including operating system and utility software
What is the purpose of application software?
Application software provides the services that the user requires
What are the general features of system software?
- Provides a platform on which other software can run
- Allows hardware and software to run without problems
- Provides an HCI
- Controls the allocation and usage of hardware resources
What does HCI stand for?
Human Computer Interface
What are the general features of application software?
- Allows a user to perform specific tasks using the computerβs resources via apps
- Might be a single program or a suite of programs
- User can execute the software as and when they require
What is the operating system?
System software running in the background of a computer system that manages basic functions of a computer
In what two forms can an HCI be in?
Command Line Interface (CLI), or Graphical User Interface (GUI)
What are some examples of application software?
- Word processor
- Spreadsheet
- Database
- Control and measuring software
- Apps
- Photo editing software
- Video editing software
- Graphics manipulation software
What is the function of control and measuring software?
- Measure physical quantities in the real world
- Control applications by comparing sensor data with stored data and sending out signals to alter process parameters
What are examples of typical system software?
- Compilers
- Linkers
- Device drivers
- Operating systems
- Utilities
What are examples of utility programs?
- Antivirus
- Anti spyware
- Disk contents analysis and repair
- File compression and management
- Backup of files
- Security
- Screensavers
Define utility programs
Software that are designe to carry out specific tasks on a computer - helping to manage, maintain, and control computer resources
How do virus checkers check for viruses?
They compare a possible virus against a database of known viruses
What is the function of defragmentation software?
Making sure that an HDD has faster read write times by rearranging blocks of data on the HDD for data to be stored in contiguous sectors
What do device drivers do?
They translate data from the operating system to a format understood by the hardware peripherals
What is a compiler?
A computer program that translates a program written in a high-level language into machine code so that it can be directly used by a computer to perform a required task.
What is a linker
A computer program that takes one or more object files produced by a compilter and combines them into a single program which can be run on a computer.
Define operating system
Software that provides an environment in which applications can run and also provides an interface between computer and human operator
List the functions of an operating system.
- Managing files
- Handling interrupts
- Providing an interface
- Managing peripherals and drivers
- Managing memory
- Managing multitasking
- Providing a platform for running applications
- Providing system security
- Managing user accounts
Where on the computer does the operating system tend to be stored and why?
On the SSD/HDD, because operating systems are usually very large programs
Define Command Line Interface (CLI)
An interface which allows communication with the computer by typing in commands using a keyboard
Define Human Computer Interface (HCI)
An interface supplied by the operating system to βhideβ the complexities of the software and hardware from the user
Define Graphical User Interface (GUI)
An interface which uses icons to represent apps and tasks which the user can select/launch by clicking on a mouse or using a touch screen.
Define interface
A user interface is a program , or suite of programs, that allows a user to interact with a computer
What are the advantages of a CLI?
- The user is in direct communication with the computer
- The user is not restricted to a number of pre-determined options
- It is possible to alter computer configuration settings
- Uses a small amount of computer memory
What are the disadvantages of a CLI?
- The user needs to learn a number of commands to carry out basic operations
- All commands need to be typed in which takes time and can be error-prone
- Each command must be typed in using the correct format, spelling, and so on
What are the advantages of a GUI?
- The user doesnβt need to learn any commands
- It is more user-friendly; icons are used to represent applications
- A pointing device such as a mouse is used to click on an icon to launch the application - this is simpler than typing in commands or a touch screen can be used where applications are chosen by simply touching the icon on the screen
What are the disadvantages of a GUI?
- Uses up considerable more computer memory than a CLI interface
- User is limited to icons provided on the screen
Define memory management
The part of an operating system that ensures the integrity, confidentiality, and availability of data
What are the functions of memory management?
- Managing primary storage, allowing data to move between RAM and HDD/SSD during the execution of programs
- Keeping track of memory locations
- Carrying out memory protection to ensure that two competing applications cannot use the same memory locations at once
What could happen if two applications used the same memory location?
- Data could be lost
- Applications could produce in correct results
- Potential security issues
- Computer could crash in extreme cases
Define security management
The part of an operating system that ensures the integrity, confidentiality, and availability of data
What are some examples of how security management is achieved?
- Ensuring that antivirus software is up to date
- Communicating with a firewall to check traffic to and from the computer
- Maintaining access rights for all users
- Offering the ability for the recovery of data when it is lost or corrupted
Define hardware management
The part of an operating system that controls all input and output devices; it is made up of sub-systems such as printer management
What are some examples of how hardware management works?
- Communicates with all input and output devices using device drivers
- Uses a device driver to take data from a file and translate it into a format that the I/O device can understand
- Ensures each hardware resource has a priority so that they can be used and released as required
- Managing I/O devices by controlling queues and buffers
Define buffers
A memory area used to store data temporarily
Define file management
Part of an operating system that manages files in a computer. For example, the ability to create, delete, copy, open, close, and rename files.
What are the main tasks of file management?
- File naming conventions which can be used (file name + extension)
- Performing specific tasks (create, open, close, delete, rename, copy, move)
- Maintaining the directory structures
- Ensuring access control mechanisms are maintained (access rights to files)
- Ensuring memory allocation for a file by reading it from the HDD/SSD
Define multitasking
A function that allows a computer to process more than one task/process at a time
Why is pre-emptive multitaking used?
To make sure the status of each process is monitored, so that processes donβt clash with each other
What are the three steps of pre-emptive multitasking?
- Resources are allocated to a process for a specific time limit
- The process can be interrupted while it is running
- The process is given a priority so that it can have resources according to its priority
Why is management of user accounts important?
- Computers often allow multiple users to log into the system
- It is necessary that user data is stores in seperate parts of the memory for security reasons
Define administrator
(when it comes to management of user accounts)
A person responsible for the upkeep and maintainence of a computer system that involves multi-user function
Define interrupt
A signal sent from a device or software to a microprocessor requesting its attention; the microprocessor suspends all operations until the interrupt has been serviced
What are examples of software interrupts?
- Attempt to divide by zero
- Two processors trying to access the same memory location
What are examples of hardware interupts?
- Pressing a key on a keyboard
- Moving the mouse
- Hardware fault
Define interrupt priority
The priority assigned to an interrupt are given a priority so that the microprocessor knows which one needs to be serviced first and which interupts are to be dealt with quickly
Once an interrupt signal is recieved, what does the microprocessor do?
The microprocessor either carries on with what it was doing or stops to service the device or program that caused the interrupt, so it can establish interrupt type and priority
Define service
(when it comes to interrupts)
When an interupt is recieved, some action needs to be taken by the processor demanding what caused the interrupt; until this is resolved (serviced), the interrupt cannot be removed to allow the microprocessor to continue
Define Interrupt Service Routine (ISR)
Software that handles interrupt requests and sends a request to the CPU for processing
What happens once an interrupt is serviced?
The Interrupt service routine is executed by loading the start address into the PC (Program Counter)
Define boot up / bootstrap loader
A small program that is used to load other programs to correctly βstart-upβ a computer system
Describe the process of computer start up
- The BIOS tells the computer where the storage device that holds the OS can be found
- It loads part of the OS that is needed and executes it (bootstrap loader)
Define firmware
A program that provides low level control for devices
The BIOS is often referred to _
Firmware
What does EEPROM stand for?
Electrically Erasable Programmable ROM
What is the EEPROM?
A flash memory chip - meaning that its contents remain even after the computer is powered down
What does the EEPROM store?
The BIOS
What does CMOS stand for?
Complementary Metal Oxide Semi-conductor
What does the CMOS store?
The BIOS settings - different from the BIOS program, stored on the EEPROM
Why do BIOS settings reset after loss of power?
The CMOS is powered up at all times via a rechargable battery on the motherboard. Therefore, the BIOS settings return to factory if the battery is removed or disconnected
Applications are run on ___
The operating system
The operating system is run on ___
The firmware
The bootloader is run on the ___
Hardware
