1. Computer Systems Nat 4/5 Computing Science
Section 2 Computer Structure:
Lesson 6: Memory

2. Lesson Aims By the end of this lesson: Pupils will be able to:
Describe of the features and uses of RAM and ROM.
Describe what is meant by a memory address

3. A quick recap We are going to look at Memory Nat 4/5 Processor
Input Devices
Output
Devices
Memory
Backing Storage
We are going to look at Memory

4. Main Memory There are two types of main memory falls : RAM RAM ROM
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Main Memory
Main Memory
RAM
ROM
There are two types of main memory falls :
RAM
Random Access Memory
ROM
Read Only Memory

5. Nat 4/5
Addressability
Your house has a unique address, made up of street, town and postcode.
No two houses have the same address!
This is the same for memory in the computer
Memory is made up of thousands of millions of storage locations
Each storage location in memory has it’s own unique address so that the processor can locate it
This address is a binary value
e.g

6. RAM – Random Access Memory
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RAM – Random Access Memory
Operating system is loaded into RAM when the computer starts up
Stores programs and data that a user is currently using
Contents of RAM are lost when the computer is switched off…
…so the user’s work must be saved to backing storage medium e.g. a hard disk
Direct-access medium = data can be read from RAM or written to RAM in any order

7. N5
Amount of RAM
Plenty of RAM improves computer performance because means:-
you can have lots of programs in memory at one time
you can run larger programs

8. ROM – Read Only Memory There is a problem with just having RAM.
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ROM – Read Only Memory
There is a problem with just having RAM.
If the contents of RAM are lost then the power is Iost how does the computer know what to do when it switches on?
ROM (Read Only Memory) is memory that will always retain its contents even when power is lost.
This concept can be used by mobile phones to store their operating systems.

9. Flash ROM

10. Summary RAM (Random Access Memory) ROM (Read Only Memory)
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Summary
RAM (Random Access Memory)
Is used to store programs and the operating system
Is volatile, which means it loses its contents when there is no power
ROM (Read Only Memory)
Contents cannot be changed and does not require power to hold data

11. Questions How can the processor identify each location in memory?
What type of memory stores the programs that the user is currently using?
What type of memory stores essential programs that make the computer work?
What type of memory is volatile?