GCSE Memory

GCSE Memory

RAM and ROM

Multiple Choice

Quick CPU recap.

Which of these registers always stores the address in memory of the next instruction to be executed?

• MAR

• PC

• MDR

• ALU

Multiple Choice

Which of these stores the data or instruction that has just been fetched from memory?

• MDR

• MAR

• Accumulator

• ALU

Multiple Select

Which of these will only ever store an address?

• MDR

• MAR

• Accumulator

• PC

Multiple Choice

Which of these directs the operation of the processor, instructing the other components what to do?

• Accumulator

• Control Unit

• ALU

• Memory

Multiple Choice

Which of these is the correct order?

• decode, execute, fetch

• execute, decode, fetch

• fetch, execute, decode

• fetch, decode, execute

Memory

• Also referred to as primary memory

• 2 Types: RAM and ROM

RAM

• Volatile primary memory

• Stores the data and instructions of the currently running software - including the operating system

• Temporary storage, as wiped when power is lost.

• Stores the data and instructions to be processed by the CPU - much faster than secondary storage

ROM

Read-Only Memory. Non-volatile

In a PC, store instructions and data required for when the computer is turned on.

The BIOS will be stored in a ROM chip and perform hardware checks and then run the bootup instructions for the operating system

RAM and ROM

• RAM volatile, ROM non-volatile

• RAM data constantly changes, ROM read-only

• RAM tends to be larger than ROM

• RAM stores currently data and instructions, ROM holds instructions on what to do when computer is switched on

Multiple Choice

Which of these is read-only?

• RAM

• ROM

• CPU

• Cache

Multiple Choice

What does volatile mean?

• Data is lost without power

• Data remains even after power loss

Multiple Choice

Which of these tends to be larger (in terms of MBs)?

• ROM

• RAM

• Cache

Multiple Choice

Which of these stores the instructions and data required to execute the currently running software?

• RAM

• ROM

• HDD

More about ROM

• All devices that have a microprocessor have a ROM chip.

• Firmware is what we refer to as their instructions on how to operate

• ROM in embedded systems usually hold all the instructions on how to work (no secondary storage)

• Important as they cannot be easily changed, they always work the same way

Multiple Choice

My computer is running slow when I open more applications. What could be the cause?

• Not enough RAM

• Not enough ROM

Virtual memory

• Used when computer low on RAM free space

• Programs in RAM are suspended and moved to secondary storage (e.g. HDD)

• This frees up space in RAM

• If the program in VM is needed, space will have to be found in RAM and the program will have to be swapped back again before if can be executed

• Like a game with party members - only those in the party gain exp

Multiple Choice

Where is virtual memory stored?

• Cache

• RAM

• ROM

• Secondary storage (e.g. HDD)

Multiple Choice

Before a process stored in virtual memory can be executed, where does it have to be transferred back to?

• RAM

• ROM

• Secondary storage (HDD)