System Software

LEARNING OBJECTIVES:

The specification states - you should be able to:

Describe the purpose of an operating system;
Describe different types of operating system: single user, multi-user, multiprocessing, multitasking and multithreading;
Explain the need for utility programs;
Describe some common utility programs: data compression, file backup, archive software and disk defragmenters;

Describe the purpose of an operatinG system

Manages memory management and internal & external storage
Manages peripheral devices – Printers
Manages files and performs file management
It controls the user interface and performs user management

Describe SINGLE user operating system

Will provide access to the computer for any one user at any given time.
Single user, single task – here the operating system is designed so that one user can effectively do one thing at any one time.
Single user, multi-tasking –allows the end user to have a number of programs running at any given time

Describe MULTI user operating system

Allows many users to run programs at the same time
The operating system must allocate its resources such as memory / processing to ensure they are balanced to each user and the overall performance of the system is satisfactory.
Time slicing may be used.

Describe multiprocessing

Requires two or more processors.
Different parts of the same task can be executed at the same time.
Each processor may be responsible for specific task or they may work together on the same task.

Describe multitasking

A single user performs more than one task at a time
but only one task is actually running at any time.
The processor switches from one task to the next
and resources are shared between the tasks.

Describe multithreading

Some processors have the ability to carry out threads (different parts) from the same task at the same time but through the effective sharing of the resources.
Threads are processes which are independent parts of the process being executed and as a result they are carried out in parallel on a single CPU.
E.g. one thread waits for the printer, another thread can perform a read task on the file.

Explain the need for utility programs

A utility program is a systems program that performs a specific task related to the management of computer functions.
It can be designed to do one or two tasks well and nothing else for example file backup, archive software, disk defragmenters and data compression.

archive software

Removes data which is no longer in regular use from the system and stores it off-line so that it is available if required.
The data may be required for legal reasons and auditing purposes or for historical uses.
Compression is often used.

Disk defragmenter

Rearranges the files stored on the disk to improve efficiency and reduce search times / access times.
Overtime, the data for a file may be stored in different parts of the disk.
The defragmenter identifies all the data for a file and stores it in contiguous space on the disk. It will also do the same with the free space.

Data Compression

Reduces the physical size of data in order to save storage space and reduce transmission time.
File compression allows users to make one or more files into a smaller zip file. Zip files are used to compress several files together for it to be able to be sent over the internet instead of sending them individually.

file backup

Backup software is designed to create an exact duplicate of data in the event of file corruption, user error or some other event that leads to data loss.
The file backup utility program may use these copies at a later stage.

System Software AS2.pptx

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