Transcript Lesson 1 - Shawlands Academy

Computer
Systems
Nat 4/5 Computing Science
Section 2 Computer Structure:
Lesson 2 :
Memory
Lesson Aims
By the end of this lesson:
Pupils will be able to:
 Describe the difference between main memory and
backing storage.
 Describe of the features and uses of RAM and ROM.
 Describe what is meant by a memory address
Nat 4/5
A quick recap
Backing
Storage
Input
Devices
Processor
Memory
 We
are going to look at the Backing
Storage and Memory
Output
Devices
Nat 4/5
Main Memory
 Main
memory falls into two types:
 RAM

Main Memory
RAM
Random Access Memory
ROM
 ROM

Read Only Memory
Nat 4/5
RAM – Random Access Memory
 Nothing
to do with male sheep!
 RAM is the computers short term memory.

If a machine is quoted as having 2GB of Ram
then it has 2GB into which programs and the
operating system is loaded into.
 RAM


is volatile.
This means that it requires power to store data.
When power is lost the contents of RAM are lost.
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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.
Nat 4/5
Addressability
 Your

No two houses have the same address!
 This

house has a unique address
is the same for memory
Each location in the computer’s memory has it’s
own unique address (in binary)
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Backing Storage
 Backing
storage are devices used to store
permanent copies of our files.
 Examples are such as:




Hard Disk Drives
USB Flash Drives
Magnetic Tapes
CD/DVD R/RW
 At
this point in the course knowing their
purpose is sufficient.
Nat 4/5
Summary

RAM (Random Access Memory)



ROM (Read Only Memory)


Is used to store programs and the
operating system
Is volatile, it loses contents when there is
no power
Contents cannot be changed and does
not require power to hold data
Backing Storage devices are used to
store permanent copies of our files and
data