Lesson Objectives
• To understand the difference between
RAM and ROM
• To be able to explain the need for ROM
• To be able to explain the purpose of RAM
Memory Recap
•
•
•
•
•
1 bit = ????
1 byte = ??? bits
1 kb = ??? bytes
1 gb = ??? Kb
1mb = ???gb
Main Memory.
• Memory has increased hugely in the last
20 years.
• 1980 - 32kb of memory standard
• 2010 - 2gb of memory standard
• “640kb of memory is the limit - more than
anyone will EVER need!” bill gates, 1981
ead
What does “Read Only”
mean?
nly
emory
When have you seen the
term before?
How does a computer start?
• When the computer is first switched on
ROM stores the instructions which it needs
in order to “boot up”.
• ROM is a type of memory that is NONVOLATILE. This means that any data which
is saved to it is not lost when the computer
is switched off.
ROM
• Because the data is “read only” it means
that it can be read but cannot be changed
by the user.
• The information on the ROM chip is often
programmed by the manufacturer.
• It contains the Boot Program which
– Performs some basic checks
– Finds the operating system
– Hands over control to the operating system
How much ROM is needed?
• ROM does not need to contain very much
data and is typically just 1 or 2MB in size
• Many devices, including music players,
mobile phones and cameras need ROM to
boot them up.
andom
ccess
emory
What is RAM?
• Have you ever worked for an entire ICT
lesson only for your computer to crash or
be “accidentally” switched off, and you’ve
lost all the work you were working on?
• That’s because it was stored in the RAM,
and as soon as the computer is switched
off it is emptied. It is VOLATILE
What is RAM?
• RAM stores the programs and data that
the computer is currently working on
• The operating system will also be loaded
into RAM in order to run.
Task 1
• You are listening to some music while you are
researching on the internet for information that you
will copy and paste into a word processed document.
Make a list of all of the things that might be stored in the
RAM memory while you are doing this task
–
–
–
–
–
–
–
–
–
The operating system for the computer
Music player software
The music file you are listening to
The web browser software
The website you are looking at
The word processor software
The word-processed file
Anti-virus software
Etc
• Computers need a lot of RAM to deal with
the large amounts of data they need to
make available at any one time for the
CPU.
• Adding more RAM to a computer will
improve the performance of that
computer by making more memory
available for direct access from the CPU.
• A typical laptop will have 4 GB of RAM or
more available.
Large Hadron Collider
Approximately 600 million times per second, particles
collide within the Large Hadron Collider.
This produces more than 15 petabytes of data a year!
At the main processing site in Switzerland they have 30
petabytes of RAM and 65, 000 cores
These super computers have 30 millions times the memory
than a normal PC
RAM and computer performance
• What happens when you try to run lots of
programs, music, video or games at the
same time?
• The computer crashes
• This is because there is not enough RAM to
complete all of those tasks.
• The more RAM you have, the more tasks
you can complete at one time.
Task 2:
• Complete the table below.
RAM
Contents
Volatile?
Size
Can contents
be changed?
ROM
Task 2:
• Complete the table below.
RAM
ROM
Contents
Operating system,
programs and data in use
by the CPU
The boot program used to start
and set up the computer
Volatile?
Yes
No
Size
Typically quite large, e.g.
8GB. More RAM enables
the computer to work on
more things at once
Usually quite small just to store
the boot program, 1 or 2 MB
Can contents Yes, contents change all
be changed? the time while the
computer is running
Not normally but can be
changed by a special ‘flashing’
operation
Task 3:
• In your exam you will need to be able to
explain how RAM can effect performance,
and suggest solutions.
• Complete the exam style question
Question 1
Give a suitable reason why Pardeep’s
computer might be running slowly
“Pardeep’s computer might be running
slowly because it doesn’t have sufficient
RAM (1 mark) to deal with all of the
applications and data that he has open at
the same time (1 mark).”
Question 2:
Suggest a related solution to help Pardeep improve
the performance of his computer (2 marks)
“The best solution to overcoming this problem is to
add extra RAM chips (1 mark). This will allow
Pardeep to increase the number of programs or
amount of data that he is able to use at the same
time (1 mark)”
Or
“Pardeep could try running less programs at one
time, closing programs that he is not using. (1 mark).
This will mean there is less pressure on the RAM and
his computer will run quicker (1 mark)”