Operating Systems Flashcards
What are the two types of software?
System software and application software
What comes under system software?
Operating systems, device drivers, firmware, language translators utility
What comes under application software?
Word processors, database software, multimedia software, graphics software, web browsers
What is an operating system?
An operating system is the core software that allows the computer to run as a useful device. It runs in the background.
What does the operating system do?
It manages hardware, the user interface and all other software.
What are the four parts of an operating system?
The kernel, the user interface, device drivers, system utilities
What is the kernel responsible for?
It is responsible for loading applications onto the memory,ensuring they do not interfere with each other and share CPU usage
What are the kernel programs?
Scheduler/dispatcher(CPU management), loader(loading and unloading applications from the memory), input/output resource management, user data security programs and IPC(inter-process communication) which allows synchronisation and communication between programs
What is the user interface?
Part of the OS which determines the way applications and users interact with hardware. Three types: CLI, MDI and GUI
CLI - command line interface
MDI - menu driven interface
GUI - graphical user interface
What are device drivers?
Software that enables the operating system to communicate with hardware
What is the function of device drivers?
To translate OS mandated function calls into device specific calls
What are system utilities?
These programs provide all basic facilities that run in the background without user interaction. This includes printer spool services, defragmentation and file management
What are the different types of operating systems?
(Single user, single application), (single user, multitasking), (single user, multithread), (multiuser multitasking), network operating systems, batch operating systems and real time operating systems
What is a single user, single application operating system? Give an example.
It can only deal with one user at a time while running one user application at a time. Example - OS of a basic mobile phone or MP3 player
What is a single user, multitasking(multiprogramming) operating system? Give an example.
This operating system is designed for a single user but it can deal with multiple applications. Example - OS on a personal computer
What is a single user, multithreading operating system?
A single user, multithreading operating system can manage multiple requests without needing to have multiple copies of the program running on the computer
What is a multi user, multitasking operating system? Give an example.
An operating system which can handle multiple people running multiple programs at the same time. This can be found on supercomputers and mainframes
What are the features of a networked operating system?
- Dealing with users logging on
- Maintaining the network connection to server
- Expand the file system to view folders on other computers
- Provide security to seperate user accounts from each other
What is a batch operating system?
A batch operating system does the same job again and again.
Where is a real-time operating system found?
A real-time operating system is found in a device where a computer is used to control a series of actions in real time
What are the two ways in which memory is managed?
- Segmentation
- Paging
What is segmentation?
Allocation and de-allocation of blocks of primary memory to allow programs to run
What is paging?
The memory manager divides memory into fixed chunks called pages. Every page is numbered and given a page table. As the main memory fills up, the memory manager will begin to store individual pages into virtual memory. This process is called paging
What is virtual memory?
When the RAM begins to fill up, the memory manager will use parts of the secondary storage device as primary memory
What are the issues faced by a memory manager?
Disk thrashing, memory leaks, memory crashes, stack overflow
paging
What is disk thrashing?
As the main memory fills up, virtual memory needs to be used. As the number of pages being swapped increases the rate of hard disk access increases. More effort is done moving the programs than actually running them.
segmentation
What are memory leaks?
When a memory location is in use, the memory manager will mark it as unavailable. A well-written memory manager will flush away the data once it no longer needs it. A badly written memory manager will not flush away the data completely and more memory will be locked up. This is called a memory leak
segmentation
What are memory crashes?
The memory manager will identify programs trying to write outside their memory boundaries and will prevent them from doing so. This will still probably crash the rogue programs but at least all the other processes are still running safely.
segmentation
What is a stack overflow?
When a data segment has been intruded by another program or a stack reaches its maximum size
What is disk partioning?
When a disk is split into logically separate parts called partitions
What are peripherals?
Peripherals are all hardware components that reside outside the CPU. E.g Keyboard, mouse and printer
What is the operating systems role in peripheral communication?
It communicates directly with the hardware(peripheral) and provides an interface between hardware and applications
What is the operating systems role in maintaining security?
- It authenticates the user through biometrics, login and password details
- It also keeps track of logs(user activity) so unauthorized user activity can be discovered
What is the operating systems role in networking?
It acts as an intermediary between applications and networks allowing sharing of resources. E.g - files
