2.3.5 System Software

Question 1

Purpose of system software

Answer 1

Every computer needs OS- this controls the hardware.

• OS holds complexity of this from user.
• OS acts an as interface between user and hardware

Question 2

What does an operating system do?

Answer 2

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.

Question 3

Multitasking

Answer 3

• 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.

Question 4

Single user OS

Answer 4

• 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.

Question 5

Multi user

Answer 5

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.

Question 6

Multiprocessing

Answer 6

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.

Question 7

Multi threading

Answer 7

• breaks the program being run into separate processes called threads
• essentially multitasking inside one application by sharing CPU resources between them rapidly.

Question 8

Utility programs

Answer 8

File backup
Data compression
Archive
Disk defragmenter

Question 9

Utility program- file backup

Answer 9

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.

Question 10

Utility programs- data compression

Answer 10

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.

Question 11

Utility programs archive

Answer 11

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.

Question 12

Utility programs disk defragmenter

Answer 12

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.