2.3.5 System Software Flashcards
Purpose of system software
Every computer needs OS- this controls the hardware.
- OS holds complexity of this from user.
- OS acts an as interface between user and hardware
What does an operating system do?
Memory management- divides the capacity of RAM between processes involved in running open applications.
Communicates with peripheral devices- printing
Provides platform on which other programs can run.
Controls hardware for other apps- Microsoft word diff on Mac and PC- have diff OS and code written w instructions that match OS.
Multitasking
- allows user to work with more than one app at any time and switch between these tasks.
- OS allocates processing time and memory to apps that are open.
- more memory can have more open concurrently
- sharing CPU resources between different apps.
Single user OS
- only 1 person operate computer at any time.
- most desktop computers are single user.
- single user single task- only 1 user cannot multitask
- single user multitasking- 1 user at a time and OS allows multiple apps to be running concurrently.
Multi user
Usually on v powerful computers usually through a network.
- processing carried out centrally on v powerful computer.
- multiple users can operate this computer at same time.
- used time slicing to share out processing time between different users.
Multiprocessing
Not multitasking.
- multiprocessing machine has several processors in it.
- each processor executes different instructions
- makes machine work faster
- GPU runs all instructions to process graphics while the CPU runs all the other instructions.
Multi threading
- breaks the program being run into separate processes called threads
- essentially multitasking inside one application by sharing CPU resources between them rapidly.
Utility programs
File backup
Data compression
Archive
Disk defragmenter
Utility program- file backup
A program that can be set to schedule the copying and pasting of files from on location to another.
Can also be used to retrieve backed up files.
Utility programs- data compression
Reduces file sizes by applying an algorithm to store repeating elements in fewer bits.
Useful for sending/ receiving files but also for long term storage.
Utility programs archive
Can be set to automatically remove data that is no longer used to store it elsewhere.
Often this data is compressed.
Archived data is not deleted.
It may be needed for historical or legal reasons.
A single file is created of archived data.
Utility programs disk defragmenter
Over time data files may get written to different parts of the hard drive.
Defragging rearranges files on the hard drive to improve efficiency by putting the files in contiguous space on the disk.
This makes it faster for the hard drive to read the file.