Memory and Storage -

Primary Storage

Memory

Memory is the place where the computer stores instructions and data

• Memory can be :

• Volatile also called Temporary memory

OR

• Non-volatile also called Permanent Memory

• Computer memory consists of any physical device capable of storing

information temporarily or permanently.

• The physical devices are called storage devices.

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Storage CategoriesComputer memory and storage is divided into three groups:

1. Primary memory

2. Secondary memory or Secondary storage

3. Off-line storage

In this lesson we are going to learn about primary memory

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Types Primary memory

Two types of primary memory :

1. Random Access Memory

2. Read Only Memory

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Features of Random Access Memory

• Data in RAM can be changed / modified /deleted

• RAM is volatile (stores data temporarily) i.e. data in RAM is lost when computer is

switched off

• RAM is the workspace of the computer. Workspace means the place where data

on which the computer is currently working /that is being processed is stored

• It is used to store:

▪ Instructions about how to process the data

▪ Part of the operating system which is controlling the hardware /software being

used currently.

• The larger the size of RAM the faster the computer will operate because it will have a

larger workspace that can hold more data/instructions at a time.

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RAM technology

Two types of RAM technology

1.Dynamic RAM (DRAM)

2.Static RAM (SRAM)

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Dynamic RAM (DRAM)

Dynamic RAM (DRAM)

▪needs to be recharged constantly otherwise it will lose its

value

▪Is less expensive than SRAM

▪consumes less power than SRAM

▪has a higher storage capacity than SRAM

▪Is the most common type of RAM used in computers.

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Static RAM (SRAM)

Static RAM (SRAM)

▪Does not need to be recharged constantly

▪much faster than DRAM

▪Very expensive to manufacture

▪Used in situations where processing speed is very important

e.g. cache memory (memory found inside the CPU).

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Features of ROM

• ROM is non-volatile memory i.e. it is permanent memory

• Contents of ROM remain even when the power is switched off

• ROM Stores the BIOS

▪BIOS consist of instructions to start-up the computer when it is

switched on

• Data in ROM is read-only i.e. It can be read but cannot be

changed, modified or deleted.

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Use of RAM and ROM in everyday objects1

Remote Controlled Toy Car( Contains both RAM and ROM)

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Functions of ROM

Remember data in ROM CANNOT be modified

• Stores data that has been set by the

manufacturer and cannot be changed by users

such as:

• remote control frequencies

• ‘start-up’ routines when the toy is first switched

on

• what happens when the buttons on the RC are

pressed (which button controls : turning left,

right, acceleration, stopping, and so on)

Functions of RAM

Remember data in RAM CAN BE modified

Stores data that and can be changed by users such

as:

• the user may wish to program in their own

steps; these new instructions would be stored

in the RAM chip

• will store the instructions received from the

remote control

• The data is lost when the toy is switched off.

Use of RAM and ROM in everyday objects 2

Microwave oven ( Contains both RAM and ROM)

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Functions of ROM

Remember data in ROM CANNOT be modified

• Stores data that has been set by the

manufacturer and cannot be changed by users

such as:

• Voltage at which it functions (240v/440v)

• ‘start-up’ routines when the oven is first

switched on

• what happens when the buttons on oven panel

are pressed (which button controls : ON/OFF,

Temperature, Time and so on)

Functions of RAM

Remember data in RAM CAN BE modified

Stores data that and can be changed by users such

as:

• the user may wish to program in their own

steps; these new instructions would be stored

in the RAM chip

• will store the instructions received from the

user : temperature , timing , auto-shutdown

• The data is lost when the oven is switched off.

Use of RAM and ROM in everyday objects 3

Refrigerator ( Contains both RAM and ROM)

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Functions of ROM

Remember data in ROM CANNOT be modified

• Stores data that has been set by the

manufacturer and cannot be changed by users

such as:

• Voltage at which it functions (240v/440v)

• ‘start-up’ routines when the oven is first

switched on

• what happens when the buttons on oven panel

are pressed (which button controls : ON/OFF,

max/min Temperatures and so on)

Functions of RAM

Remember data in RAM CAN BE modified

Stores data that and can be changed by users such

as:

• the user may wish to program in their own

steps; these new instructions would be stored

in the RAM chip

• Every user can set their own min/max

temperatures

• The data is lost when the refrigerator is

switched off and has to be set again.

Homework

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Homework 1

(a) Explain three ways that RAM is different to ROM.

1 ................................................................................................................................................

2 ................................................................................................................................................

3 ................................................................................................................................................

(b) Describe one item that is stored in RAM.

..............................................................................................................................

(c) Describe one item that is stored in ROM.

..............................................................................................................................

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Homework 2

• A computer uses RAM and ROM to store data.

• (a) The table contains three statements about RAM or ROM.

• Tick (✓) to show whether each statement describes RAM or ROM.

• (b) Circle the storage category that includes both RAM and ROM.

Primary Secondary Off-line

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Homework 3

A remote-controlled model aeroplane contains both RAM and ROM. The model aeroplane

receives radio signals from its remote control. It can only receive radio signals of a certain

frequency. The manufacturer sets this frequency and the owner cannot change it. The owner of

the model aeroplane can input their own sequence of movements from an interface underneath

the aeroplane.

Describe the purpose of each of the two types of memory supplied with the aeroplane.

ROM ............................................................................................................................. .............

............................................................................................................................. .............

RAM ............................................................................................................................. ............

..........................................................................................................................................

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