memory and storage - primary storage · 2020-04-16 · memory memory is the place where the...
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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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