14 terms

Memory

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What is volatile memory?
The memory content is lost when the power is turned off eg RAM
What is non-volatile memory?
The memory content is not lost when the power is turned off eg ROM
What are the two types of memory?
Volatile and non-volatile
What is the difference between volatile and non-volatile memory?
Volatile memory requires electricity or some kind of current to store information, and nonvolatile memory does not
What is the purpose of volatile memory?
1) Can protect sensitive information as it becomes unavailable on power down
2) Faster to read from and write to

RAM:
- the operating system
- applications
- the graphical user interface (GUI)

Main memory
What is the purpose of non-volatile memory?
Can retrieve stored information even after having been power cycled
ROM
The computer's:
-BIOS
-initial instructions
-bootstrapping instructions
When should volatile memory be used?
- the operating system
- applications
- the graphical user interface (GUI)
- doesn't matter if the computer is turned off
When should non-volatile memory be used?
ROM
The computer's:
-BIOS
-initial instructions
-bootstrapping instructions
What is virtual memory?
1) A section of a computer storage drive which is temporarily used as RAM

2) Memory that appears to exist as main storage although most of it is supported by data held in secondary storage, transfer between the two being made automatically as required
When should virtual memory be used?
-When a computer system has insufficient memory
-When running a program or a combination of programs too large to fit into the memory
-When the main memory is small or limited
-When the main memory is all in use
What is cache memory?
Small and very fast storage found close to the processor
What is the purpose of virtual memory?
If a computer lacks the random access memory (RAM) needed to run a program or operation, virtual memory can be used to compensate.

Virtual memory combines a computer's RAM with temporary space on the hard disk. When RAM runs low, virtual memory moves data from RAM to a space called a paging file.
What is the purpose of cache memory?
Frequently used instructions are stored in the cache, so that they don't have to be fetched from the main memory
Therefore instructions stored in the cache memory can be accessed faster than instructions stored in the main
memory
Explain the fetch-decode-execute cycle
1) The instructions are held in memory
2) The processor loads the instructions from secondary storage to memory
3) The instructions are stored in a contiguous format
4) The processor fetches an instruction from memory, decodes the instruction and then executes it
5) The result may be stored back into memory
6) The process is repeated continuously