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RAM, ROM and Cache

Random Access Memory (RAM)

RAM is a type of very fast memory that is used to temporarily hold data about currently running programs. When you load any file from the hard drive there is a lag between the request and the data being sent, this would cause massive slow down of the CPU if data was constantly being requested from the hard drive. Instead a single request is sent to the hard drive when the program loads and the whole program is loaded in to RAM. The RAM is electronic memory and all the data is stored in flop flop circuits using electrical currents and transistors. This means that there is very little latency and there the computer loads the program much faster than if it wasn’t used. However because RAM data is stored electronically, RAM is volatile – once power is lost all data is lost as well.

Read Only Memory ( ROM)

Read only memory is mainly used in a PC to store the tiny mini operating system called the BIOS. The BIOS data is flashed to the ROM chip when the motherboard is made and does not change for it’s entire lifetime (hence the term Read Only). If you want to update the BIOS, you need to flash the ROM chip.

The BIOS is responsible for doing a system hardware check before the system starts to make sure all the connected devices are functioning. Once it has completed the check it boots up the operating system.

Cache Memory

Cache memory is small amount of RAM located on the CPU itself. It stores commonly used data that is being constantly used by the operating system, allowing for even faster access than the RAM.


Virtual Memory

Often when you open up multiple programs at the same time, or if you are completing memory intensive tasks ( such as modern 3D gaming) your computer will run out of available RAM. This would potentially cause the computer to crash as it would have to dump the contents of the RAM. Instead it creates an area of pretend RAM on your main hard disk, storing excess RAM instead of a page file. This stops the PC from crashing, but is much slower than RAM, so your PC will often slow down or become unresponsive when this is necessary.


Flash Memory

Flash memory is a form of ROM that is commonly used in embedded devices such as washing machines or smart tvs.

Flash memory is:

  • Very reliable
  • Relatively Secure( because it requires the memory to be flashed, files can’t just be copied / edited in place.