All data within the computer is held in 'memory' of one kind or another.
The two types of storage for program control are:
- Hard Disk - vast storage but relatively slow
- 'Volatile memory - RAM - Used to store data that the CPU requires to run an application.
The reason for this is to do with speed of access. The hard disk stores many gigabytes of data but it takes an age to get to it compared to the running speed of the CPU.
Consider these numbers:
( 1 nano-second is a thousand millionth of a second)Time to access data on a hard disk: 7,000,000 nano-seconds
Time it takes the CPU to process some data: less than a nano-second.
If you scaled this up so that it took the CPU 1 second to process some data then the hard disk would take nearly 3 months to supply that data!
What is needed is fast memory that can temporarily store all the information needed to run an application. This fast memory is called Random Access Memory (RAM) and it can typically supply data in about 3 nano-seconds - much closer in speed to the CPU.
Ideally, when you are using a PC, the application that you have open will be fully loaded into RAM from the hard disk and all of your open documents will also be held in RAM. When this happens, the hard disk is no longer limiting the speed of the computer.
So increasing the amount of RAM is likely to improve performance.
A keen game player would want to run with 1 Gigabyte of RAM rather than 512Mbyte because all the graphics are ready to use in fast memory rather having to be fetched from hard disk.
However, once the application is making maximum use of RAM, then putting even more into the machine will not improve performance. It is a balance.
