Memory controller

A memory controller, also known as memory chip controller (MCC) or a memory controller unit (MCU), is a digital circuit that manages the flow of data going to and from a computer's <a href="/facts/Main_memory/wPHKFpdx">main memory</a>. When a memory controller is integrated into another chip, such as an integral part of a <a href="/facts/Microprocessor/Fx9CaQht">microprocessor</a>, it is usually called an integrated memory controller (IMC).
Memory controllers contain the logic necessary to read and write to <a href="/facts/Dynamic_random-access_memory/koI9FGo5">dynamic random-access memory</a> (DRAM), and to provide the critical <a href="/facts/Memory_refresh/Wg1uQekt">memory refresh</a> and other functions. Reading and writing to DRAM is performed by selecting the row and column data addresses of the DRAM as the inputs to the <a href="/facts/Multiplexer/lVro0Sfz">multiplexer</a> circuit, where the <a href="/facts/Demultiplexer/lVro0Sfz">demultiplexer</a> on the DRAM uses the converted inputs to select the correct memory location and return the data, which is then passed back through a multiplexer to consolidate the data in order to reduce the required <a href="/facts/Bus_(computing)/R45TKwS7">bus</a> width for the operation. Memory controllers' bus widths range from <a href="/facts/8-bit/2CkhLNoH">8-bit</a> in earlier systems, to 512-bit in more complicated systems, where they are typically implemented as four <a href="/facts/64-bit/AgvkQHkM">64-bit</a> simultaneous memory controllers operating in parallel, though some operate with two 64-bit memory controllers being used to access a <a href="/facts/128-bit/fo1QpdNj">128-bit</a> memory device.
Some memory controllers, such as the one integrated into <a href="/facts/PowerQUICC/aLq75CKU">PowerQUICC</a> II processors, include <a href="/facts/Error_detection_and_correction/o2rH8e3n">error detection and correction</a> hardware. Many modern processors are also integrated <a href="/facts/Memory_management_unit/tJQtAQzI">memory management unit</a> (MMU), which in many <a href="/facts/Operating_system/8XTuvMh2">operating systems</a> implements <a href="/facts/Virtual_addressing/ILxbMjgv">virtual addressing</a>. On early x86-32 processors, the MMU is integrated in the CPU, but the memory controller is usually part of <a href="/facts/Northbridge_(computing)/XFbfH4Kl">northbridge</a>.

Memory controller open-in-new

Memory controller