The PC has two basic types of memory - Random Access Memory (RAM) and Read Only Memory (ROM). RAM is by far the faster of the two types of memory. In fact, RAM is often used to shadow the BIOS ROM to improve its performance during the boot process. When volatile memory loses its power source, it also loses its contents. Most types of RAM, especially DRAM, are volatile, and that's why when you turn off the PC's power, everything in RAM is lost. Non-volatile memory, like ROM and other types, does not lose its contents when the power source is lost.
RAM is available in different formats and has to be compatible with the motherboard.
The popular formats are
- DRAM (Dynamic RAM)
- EDO RAM (Extended Data Output RAM)
- RIMM (Rambus In-line Memory Module)
- SRAM (Static RAM).
- VRAM (Video RAM) and WRAM (Windows Accelerator Card RAM) are used on video cards as graphics memory.