5.1. Operating System Flashcards
1
Q
Need for OS
A
- A set of programs designed to run in the background
on a computer system which - Controls operation of computer system
- Provides a user interface
- Controls how computer responds to user’s
requests - Controls how hardware communicate
- Provides an environment in which application
software can be executed - OS hardware is unusable without an OS, as the OS
acts as an interface since it controls communication
between user and hardware
2
Q
Key Management Tasks
A
- (Main) Memory Management
- Memory protection to ensure 2 programs do not
try to use same memory space
Paging - Use of virtual memory
3
Q
File Management
A
- Provides file naming conventions
- Maintains a directory structure
- Allocates space to particular files
4
Q
Security Management
A
- Proves usernames & passwords
- Ensures data privacy
- Prevents unauthorized access
- Carries out automatic backup
5
Q
Hardware (input/output/peripherals) Management
A
- Installation of appropriate driver software
- Controls access to data sent to and from
peripherals - Receives & handles interrupts from hardware
devices
6
Q
Processor Management
A
- Enables multiprogramming and multitasking
- Resolution of conflicts when 2 or more processes
requires the same resource - E.g. via Round-robin method
7
Q
Utility Software
A
- Disk Formatter
- Virus checker
- Defragmentation Software
- Disk contents analysis/disk repair software
- File Compression
- Back-up Software
- Program Libraries
- Dynamic Link Library (DLL) files
8
Q
Disk Formatter
A
- Prepares a hard disk to allow data to be stored on
it - Deletes any existing data on disk
- Performs formatting, process where computer
‘draws lines’ on disk surface to split it into small
areas
9
Q
Virus checker
A
- Checks for and then removes any viruses found
- Constantly checks all incoming and outgoing files
10
Q
Defragmentation Software
A
- Files can be big so have to be stored in multiple
sectors, which can result in fragmentation
(contents of file scattered across >2 noncontiguous sectors) - Fragmentation slows down disk access and thus
the performance of the entire computer. - Defragmenting software works by physically
reorganizing disk contents (files) such that they
are stored in contiguous sectors. - This defragmentation reduces number of
movements of the read/write heads require to
access the disk contents, hence increasing
computer performance - The defragmentation also creates larger
contiguous free space regions
11
Q
Disk contents analysis/disk repair software
A
- Software utility for visualization of disk space
usage - Gets size for each folder and files, and generates a
graphical chart showing disk usage distribution
according to folders or other user defined criteria. - Allows disk to report errors (e.g. “bad sector”)
- Software will attempt to offer a solution
12
Q
File Compression
A
- Reduces file size by removing redundant data in
files - Causes improvements in the computer’s
performance by reducing the data that needs to
be stored
13
Q
Back-up Software
A
- Makes copy of files on another storage medium in
the event of a hard drive failure, user error,
disaster or accident. - Should be a regular process
- Can provide synchronization between devices
14
Q
Program Libraries
A
- Pre-written code that can be linked to a software
under development without any amendments - Can perform common or complex tasks
Takes the form of classes - Benefits:
Saves time: less code needs to be written
Smaller testing time: pre-tested and used by
others
Library file be a complex algorithm which the user
need not understand for using it
15
Q
Dynamic Link Library (DLL) files
A
- Shared library file that contains code and data
- Code saved separately from the main .EXE file,
reducing the .EXE file’s size - Code only loaded to main memory when required
- DDL file can be made available to several applications
simultaneous, thus reducing strain on memory - DLL files act as modules in more complex programs,
making it easier to install and run updates
