Double Data Rate

An advanced memory technology primarily used for RAM (Random Access Memory) in computers and electronics. Its core innovation allows for data to be transferred twice per clock cycle—on both the rising and falling edges of the clock signal. This effectively doubles the data throughput compared to older Single Data Rate (SDR) memory without increasing the actual clock frequency.

Clock Cycle

The fundamental time unit for synchronizing operations. In DDR, one clock cycle enables two data transfers.

Data Transfer Rate (MT/s)

The speed of DDR memory is measured in Megatransfers per second (MT/s), indicating millions of data transfer operations per second. A memory module with a 100 MHz clock has a data rate of 200 MT/s.

Prefetch

A key architectural feature where the memory fetches a larger chunk of data (e.g., 2n bits for DDR1) from the storage array internally, which is then transmitted in smaller pieces over the bus using the double-data-rate technique.

SDRAM (Synchronous Dynamic RAM)

The type of memory DDR is based on. It is "synchronous," meaning its operations are synchronized with the system clock.

Generations (DDR2, DDR3, DDR4, DDR5)

Successive generations of DDR technology. Each iteration increases performance through higher speeds, improved bandwidth, lower voltage, and architectural enhancements like larger prefetch buffers.

DIMM (Dual In-line Memory Module)

The physical circuit board that holds the DDR SDRAM chips and is plugged into the motherboard.

Bandwidth

The total data transfer capacity, calculated as (Data Transfer Rate) x (Bus Width in bits/8). Higher bandwidth indicates a faster data pipeline.

Tag：DDR