Memory

Tasks to help students understand what computer memory does.

1) Revise with students the computer model for a typical PC or laptop. Put the model on the whiteboard.

2) Ask them to discuss in pairs, then discuss as a class:

     a) what would the consequence be if the RAM in the diagram were replaced with a ROM chip.
     b) what would the consequence be if the RAM and storage were swapped around in the diagram?
     c) what would the consequence be if RAM were non-volatile?
     d) what would the consequence be if storage devices were volatile?

(ROM is read only, so new applications and files couldn't be loaded from the storage devices. The CPU is a solid state device. If it had to work with a non-solid state device, it would be very slow. RAM is designed to be as fast as CPUs. If RAM were non-volatile, you couldn't write to it. If storage devices were volatile, you couldn't save anything long term, when the power was switched off.)

4) Hand out the following. Ask pupils to cut up the senetences. (Copy into a word processor and use font size 14). In pairs, put the sentences into the correct order, to describe what happens when you boot-up a computer.

     Once the boot files have been applied, the computer is ready to use.
     These are also found on the hard drive.
     Once the operating system has been loaded, the boot files are located.
     E.g. to display your wallpaper, to start your virus software and firewall.
     And finds the operating system.
     It loads that into RAM.
     This program checks the health of the computer and reports any problems on the screen.
     Once you turn the power on, the program in ROM starts.
     They are used to apply your custom-settings.
     It then goes to the hard drive.
     Booting up your computer simply means to turn the power on.

5) Can any of the sentences be swapped around and the sequence will still make sense?

The correct sequence is: 

     Booting up your computer simply means to turn the power on.
     Once you turn the power on, the program in ROM starts.
     This program checks the health of the computer and reports any problems on the screen.
     It then goes to the hard drive.
     And finds the operating system.
     It loads that into RAM.
     Once the operating system has been loaded, the boot files are located.
     These are also found on the hard drive.
     They are used to apply your custom-settings.
     E.g. to display your wallpaper. to start your virus software and firewall.
     Once the boot files have been applied, the computer is ready to use.

Students should write out or glue the sentences into the correct order.

6) 'Normal' RAM is usually known as Dynamic Random Access Memory, or DRAM. Cache is usually known as SRAM, or Static Random Access Memory. Students should find out what SRAM is used for.

7) Point out that RAM and ROM are sometimes known as 'Primary memory' and 'Immediate Access Storage'. Can they guess why? (They work directly with the CPU.)

8) Storage devices are often called 'secondary storage devices'. Can they guess why? (They do not work work with the CPu directly. Files and programs must be moved into RAM first.)

9) Students should be given a piece of A4 paper and asked to draw the model of a computer. They should modify the original diagram, however, so it includes ROM and Cache (don't forget the arrows) and the additional names. They should do this as a neat diagram and in colour.