Random Access Memory and Your Computer

Random Access Memory, commonly known as RAM, is an essential part of data transfer and storage for every computer. Allowing for every byte of data to be accessed, from data values to complex computer programs, RAM proves its worth each time you access something or more to the point anything on your computer. The random in RAM simply means that any part of the data can be accessed and returned in constant time. Constant time is the amount of time needed to bring forth the information requested when the amount of data being brought forth is not factor. RAM usually deals with volatile types of memory, which is deleted when the computer is turned off.

Read-Only Memory, commonly known as ROM, is another form of RAM. Information and data stored in ROM is semi-permanently stored, in which that it is difficult and time consuming to modify. ROM is normally used to store and distribute firmware. Firmware consists of software usually tied directly to a component of hardware, such as a mouse driver, that doesn't require excessive updates. Mask ROM is the oldest form of ROM in a solid state; meaning that it can never be modified. More advanced ROM, such as EPROM and EEPROM, have the capability to be erased and re-programmed multiple times. Because the task of re-programming is a long and slow process that rarely occurs, and it often limits individual memory locations from being written by random access which is possible with reading ROM.

Further extensions of RAM are DRAM and SRAM. DRAM (Dynamic Random Access) uses separate capacitors to store each bit of data within an integrated circuit. DRAMs capacitors slowly discharge energy so their power must be periodically refreshed. With each bit only needing one capacitor DRAM can reach a much greater density than SRAM. SRAM (Static Random Access Memory) requires six capacitors per bit, but unlike DRAM refreshing is not necessary. DRAM and SRAM are listed as volatile memory because its data is lost when the computer loses power, however for a short time after power lose DRAMs data can still be retrieved.

SDRAM (Synchronous Dynamic Random Access Memory) is classified as solid state computer memory; meaning it relies completely on semiconductors, transistors, and chips. SDRAM reacts as quickly as possible as the input it receives changes. (Ex. Typing in a new web address and pushing enter, while the current web page is still loading, SDRAM stops loading the initial site and starts loading the new site as quickly as it can, this process is also known as pipelining.) Reacting to data changes so quickly is possible because SDRAM is directly connected to the computers processor.

Pipelining allows for a set amount of time to pass before the requested data is shown. The delay between when the data is requested and when the data is shown is known as latency. Latency occurs because the computers Central Processing Unit, also known as the CPU, is a great deal faster than the SDRAM thus the computer is waiting for the SDRAM to catch up before it continues. Latency is one of the most important factors in choosing your computers SDRAM.