Paging, Segmentation & Virtual Memory

Paging

Operating systems are responsible for managing memory for the user. Managing memory can be done by paging or by segmentation.

Paging

Paging splits the main memory (RAM) into 4 kb sections known as pages.
When programs run they are allocated a set number of pages to run in.
Programs can be split across lots of pages that are non-contiguous (not all together).
This is managed by a table map.

Performance

Performance is not affected by having non-contiguous pages for your program.
Any pages being used that are not active can be sent to virtual memory to free pages up for other tasks.
Performance may be affected if some programs are split (e.g. when parts of a looping function are split across pages)

Segmentation

Operating systems are responsible for managing memory for the user. Managing memory can be done by paging or by segmentation.

Segmentation

There is no physical split in segmentation like in paging.
Each program is given a logical division of memory to operate in.

Segmentation process

When a program loads, it is given enough memory for the parts it is currently trying to load.
The rest of the program is kept in storage until needed, but the logical section given to the program will need to be made bigger.
Programs that are split across logical splits (non-contiguous) suffer greatly for not being together.

Virtual memory

Segmentation can also use virtual memory to store unused parts of programs in virtual memory to free space for something else.

1Components of a Computer

1.1Structure & Function of the Processor

1.1.1Structure of the CPU

1.1.2Fetch, Decode, Execute Cycle

1.1.3Factors Affecting CPU Performance

1.1.4CPU Architecture

1.2Types of Processors

1.2.1CISC & RISC

1.2.2Multicore & Parallel Cores

1.3Input, Output & Storage

1.3.1Computer Systems

1.3.2Magnetic Storage

1.3.3Optical Storage

1.3.4Types of Optical Storage

1.3.5Types of Memory

1.3.6Flash Memory

1.3.7Virtual Memory

2Software & Software Development

3Exchanging Data

4Data Types, Data Structures & Algorithms

4.1Data Types

4.1.1Data Types

4.1.2Arrays & Strings

4.1.3Representing Numbers

4.1.4Binary Arithmetic

4.1.5Hexadecimal

4.1.6Converting Binary Numbers

4.1.7Floating Points in Binary

4.1.8Floating Point Arithmetic

4.1.9Bitwise Manipulation

4.1.10Character Sets

4.2Data Structures

4.2.1Arrays, Linked Lists & Queues

4.2.2Graphs, Hash Tables & Stacks

4.2.3Trees

4.3Boolean Algebra

4.3.1Computational Logic

4.3.2Boolean Logic

4.3.3Karnaugh Maps

4.3.4Boolean Identities

4.3.5Flip Flops & Adder Circuits

5Legal, Moral, Cultural & Ethical Issues

5.1Computing Related Legislation

5.1.1Data Protection Act (1998)

5.1.2Computer Misuse Act (1990)

5.1.3Copyright Designs and Patents Act (1988)

5.1.4Regulation of Investigatory Powers Act (2000)

5.2Moral & Ethical Issues

5.2.1Online Activity Tracking

5.2.2Censorship

5.2.3Cultural Issues

5.2.4Environmental Issues

5.2.5Layout, Colour Paradigms & Character Sets

6Elements of Computational Thinking

6.1Thinking Abstractly

6.1.1Abstraction

6.2Thinking Procedurally

6.2.1Decomposition

6.3Thinking Logically

6.3.1Pseudocode & Flow Diagrams

7Problem Solving & Programming

7.1Programming Techniques

7.1.1Programming Fundamentals

7.1.2Modularity

7.2Programming Construction

7.2.1Integrated Development Environments

7.2.2Testing

8Algorithms

8.1Algorithms

8.1.1Interpreting, Correcting & Completing Algorithm

8.1.2Sort Algorithms

8.1.3Insertion & Merge Sort

8.1.4Search Algorithms

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