Operating system Flashcards
Define OS
this is the software that manages and controls all the computer’s hardware.
describe the OS
- it is loaded into RAM once the computer is switched on.
- it runs the entire time the computer is turned on.
- it is the platform on which all application software runs.
list the communication link in order
userapplicationOShardware
- the OS serves as a link between application software and the computer’s hardware
- the OS provides a platform on which application software can run.
list the functions and services of the OS
- memory management
- process/task management
- device management
- file management
- security
- user interface
describe memory management
- the OS assigns a certain amount of memory to running programs.
- if there is not sufficient RAM then the OS will use part of the hard disk (a space allocated for Virtual memory)
define virtual memory
memory that appears to exist as main storage although most of it is supported by data held in secondary storage, transfer between the two being made automatically as required.
describe process management.
part 1
- multiple software are normally executed at once (by users and in backgrounds)
- the OS assign resources (such as printers and hard disk) in a controlled manner to processes currently running.
describe process management
part 2
- protects one program from corrupting another program’s data
- if a program crashes, the OS will kill it or shut it down without affecting other programs.
- the OS assigns each program a certain amount of CPU time (to users it may appear that several programs are running at the same time.)
describe security
- provides security by requiring users to authenticate themsevles [username and password]
- the OS manages a user’s home directories, by keeping them safe from other users.
- the OS maintains a list of permissions controls user access- applies to shared files, folders and peripheral devices.
- the OS will have firewall systems on networks to :
1. restrict incoming and outgoing traffic
2. prevent unauthorised access
describe user interface
- the OS provides an interface to allow the user to interact with and operate the computer.
- allows for the starting and stopping of programs, switching between programs, and management of files. (create, move, copy and delete.)
list the main types of interfaces.
- command line interface (CLI) [user types a series of commands using a keyboard
- graphical user interface (GUI) [user uses a mouse or pointing device]
describe device management
- transparently controls all hardware devices (disk drives, printers, screens.)
- the OS schedules when a device can be used by a process and for how long. for example, a printing of one file can start only when another is completed.
describe file management
- the OS keeps a tract of where different files can be found using an index
- the OS controls the disk by telling it which data to save and in what sector.
- the user tells the OS logically what folder to save the file in and what to name the file.
how RAM and Virtual memory work with each other
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different process states
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