Dynamic random-access memory (
DRAM) is a type of
random-access memory that stores each
bit of data in a separate
capacitor within an
integrated circuit. The capacitor can be either charged or discharged; these two states are taken to represent the two values of a bit, conventionally called 0 and 1. Since capacitors leak charge, the information eventually fades unless the capacitor charge is
refreshed periodically. Because of this refresh requirement, it is a
dynamic memory as opposed to
SRAM and other
static memory.
The main memory (the "RAM") in personal computers is dynamic RAM (DRAM). It is the RAM in desktops,
laptop and
workstation computers as well as some of the RAM of
video game consoles.
The advantage of DRAM is its structural simplicity: only one
transistor and a capacitor are required per bit, compared to four or six transistors in SRAM. This allows DRAM to reach very high
densities. Unlike
flash memory, DRAM is
volatile memory (cf.
non-volatile memory), since it loses its data quickly when power is removed. The transistors and capacitors used are extremely small; billions can fit on a single memory chip.