Operating System
- Created by: harveyweinstein
- Created on: 13-05-18 15:00
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- Systems Software
- OS
- Device Drivers
- Allows operating systems to communicate with hardware
- Essentially acts as a translator between hardware and software
- User Interface
- Allows the user to interact with a computer system
- Graphical User Interface are the most popular as they are visual and interactive
- Multitasking
- The OS helps the CPU carry out multitasking by efficiently managing memory and CPU processing time
- When an application is opened, the OS moves the neccesary parts to memory, followed by required additional parts.
- To run multiple applications, the OS makes sure the applications don't interfere. It does this by using a memory manager to allocate memory addresses.
- Only one application can be processed at any time so the OS divides CPU time into the most efficient order
- When required, the OS moves data to and from virtual memory
- Only one application can be processed at any time so the OS divides CPU time into the most efficient order
- To run multiple applications, the OS makes sure the applications don't interfere. It does this by using a memory manager to allocate memory addresses.
- When an application is opened, the OS moves the neccesary parts to memory, followed by required additional parts.
- The OS helps the CPU carry out multitasking by efficiently managing memory and CPU processing time
- File and Disk Management
- File Management is the organisation of data into a usable hierarchical structure
- The hard disk is also managed, it splits the physical disk into storage sectors, decides which sector to write data and keeps track of free space
- Ideally the data for a single file would be placed in adjacent sectors, but this isn't always possible
- User Accounts
- Single-User: Only allow one user on at once, most common type of OS even if there are multiple accounts
- Multi-User: Allow several people on at once. Mostly used by mainframes such as ATMs
- Responsible for user account control - allow different users to gain access to their own information but not to other user's information stored on the same system
- Often has some form of anti-theft measures - such as passwords or pins. Some systems have fingerprint or retina scanners
- Device Drivers
- Utility Software
- Disk Defragmentation
- As files are moved, deleted, or change size lots of small gaps appear which new files fill in. Over time, the hard drive becomes more fragmented which slows the performance down.
- Defragmentation software reorganises data to put fragmented files together. It also moves files to collect all of the free space.
- Fregmented files does not affect SSDs as they have no moving parts.
- As files are moved, deleted, or change size lots of small gaps appear which new files fill in. Over time, the hard drive becomes more fragmented which slows the performance down.
- Backup Utilities
- Backup utilities allow for scheduling of regular backups, creating rescue disks and options for full or incremental backups
- Full backups are when a copy of every file is taken, this uses a lot of storage space but is faster to restore from
- Incremental backups are when only the files created or edited since the last backup are copied. This saves time and space but will take longer to restore.
- Compression Software
- Reduces the size of files. Used frequently on the internet as .zip and .rar files. Need to be extracted before the can be used
- Encryption Software
- Scrambles data to stop third-parties from viewing it. Can be decryption using a special 'key'
- Disk Defragmentation
- OS
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