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DAVJ277 1.2.1
J277 GCSE CS 1.2.1 Primary Storage - RAM and ROM
Question | Answer |
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What is the purpose of RAM in a computer system? | Purpose: stores programs currently in use Stores files currently in use. Stores parts of the operating system currently in use. |
How does RAM differ from ROM? (remember to give both sides when comparing) | RAM is Volatile (data lost when power is off—not suitable for long term storage) (ROM isn’t volatile) RAM is Easily expandable (unlike ROM) RAM’s Contents changes frequently. Contents of ROM don't normally change. Purpose of RAM: stores programs currently in use Stores files currently in use. Stores parts of the operating system in use. Purpose of ROM stores the start up instructions of the computer (BIOS) |
What is the purpose of ROM in a computer system? | Purpose: stores boot up instructions/BIOS, used to start computer, loads operating system. |
How does ROM differ from RAM in a computer system? | ROM is Non-volatile (data retained when power is off) ROM is Read only—contents hardly ever change Purpose of ROM: stores boot up instructions/BIOS, used to start computer, loads operating system. |
How does increasing RAM affect the performance of a computer? | More instructions/programs/applications can run at the same time/be held in RAM means the computer can multitask more programs… as there is more memory for running programs and data to be loaded into Programs will run faster…due to less use of virtual memory |
Why does increasing RAM not always improve the performance of a computer? | If a computer is not utilising all the RAM it currently has performance will not be improved by adding more RAM. |
What is Virtual memory? | Part of hard drive (secondary storage) is used as virtual memory (VM) to allow more programs to be loaded when RAM is full. Data not recently used in RAM is moved to VM to free up space in RAM. Makes computer slower than just using RAM as data needs to be swapped between RAM and VM and back again to RAM to be executed. |
Why does using virtual memory make the computer slower? | Data needs to be swapped from VM to RAM in order to be fetched by the CPU Moving data between RAM and VM takes processor time Excessive use of VM causes disk thrashing which decreases performance |