Neon-komputadór

Memory

Usually this refers to the memory, or more specifically the Random Access Memory (RAM), that holds all the programs and data that the processor is using at a given time. It can differentiated from Read Only Memory (ROM) which usually can't be modified or disk memory (also known as storage). RAM is dynamic memory; information can be sent to the RAM any number of times and volatile - very importantly, as we all have experienced losing work in this way - it is only stored whilst there is electricity in the system. The quantity of memory is measured in bytes - usually megabytes on current machines. Having a higher amount of memory on your computer allows the machine to run more programs, more sophisticated programs and manipulate more data.

ROM is worth discussing very briefly. It is incorrect to view ROM as somehow being very different to RAM (this is reason it's being discussed here). ROM is simply RAM that usually can't be written to nor is the data volatile. In terms of architecture it is very much the same however. ROM is invariably used for the BIOS (Basic Input/Output System) - the first program that a computer loads when the power is turned on.

There are two basic types of RAM, DRAM (Dynamic RAM) and SRAM (Static RAM). The former is more common as it is inexpensive and capable of a higher memory capacity on each chip. A slight disadvantage is that because the memory cells are tiny capacitors they require to be constantly refreshed with electrical charge. This takes away processor time from other tasks, and in older machines it could take up to 10-15 of CPU time. With modern CPUs running at the speed of hundreds and even thousands of megahertz, this is no longer a real problem.

This does not mean that Static RAM is out of the picture however. Its role has just come quite specialized. Static RAM is about thirty times as expensive and thirty times larger than DRAM. But it does have one great advantage - speed. Like the speed of a processor is measured in megahertz, the speed of memory is expressed in nanoseconds - a billionth of a second, or about the time it takes a beam of light to travel the distance of a standard ruler (megahertz and nanoseconds however can be converted via a simple formula). Basically, DRAM is too slow to fully take advantage of the speeds that modern processors can run at. So computer architecture places SRAM in the processor cache to make better use of the CPU clock cycle.

Computers at the Ministry of Foreign Affairs and Cooperation have between 32 and 96 megabytes of RAM on the older Compaq machines and 256 megabytes of RAM on the new Hyundia machines.