DDR
RAM · 5 specs
Direct Answer
DDR SDRAM (sometimes called DDR1), finalized by JEDEC in 2000, was the first double-data-rate memory standard -- transferring data on both the rising and falling edge of the clock signal. It used a 184-pin DIMM for desktops and a 200-pin SO-DIMM for laptops, running at 2.5V.
Source: JEDEC JESD79 · Last reviewed Aug 28, 2026
Specs
| JEDEC Standard | 2000 (JESD79) |
| DIMM Pins | 184 |
| SO-DIMM Pins | 200 |
| Nominal Operating Voltage | 2.5 (2.6V for DDR-400) V |
| Data Rate Range | 200–400 (DDR-200 to DDR-400) MT/s |
The First Double-Data-Rate Standard
JEDEC finalized the original DDR SDRAM standard in June 2000, though development had been underway since 1996 and early products reached the market by 1998. Its defining feature -- and the source of the name -- is transferring data on both the rising and falling edges of the clock signal, doubling throughput over the older single-data-rate SDRAM without raising the clock speed itself. DIMMs ran 184 pins for desktops and 200 pins for laptop SO-DIMMs, at a standard 2.5V (2.6V for the fastest DDR-400 variant).
Every DDR generation since has used a deliberately different notch position and/or pin count specifically to make it physically impossible to insert into the wrong generation's slot -- DDR itself set that pattern by using a single locating notch, compared to the two notches used on the older SDR SDRAM it replaced.