Dual Inline Memory Module (DIMM)

DIMM (Dual Inline Memory Module)

DDR SDRAM chips :

 Standard DIMMs have 168 pins, one notch on either side, and two notches along the contact area.

DDR DIMMs

on the other hand, have 184 pins, two notches on each side, and only one notch along the contact area.

All DIMMs are either 64-bits (non-parity) or 72-bits (parity or error correcting code [ECC]) wide (data paths).

Dual Inline Memory Module (DIMM)

 A typical 168-pin SDRAM DIMM. The one shown here is 72-bit, although the dimensions would be the same for 64-bit

The pins are numbered from left to right and are connected through to both sides of the module on the SIMMs. The pins on the DIMM are different on each side, but on a SIMM, each side is the same as the other and the connections carry through.

Double Data Rate Dual Inline Memory Module (DDR-DIMM)

A typical 184-pin DDR DIMM. The one shown here is 72-bit, although the dimensions would be the same for 64-bit.

DDR SDRAM

DDR SDRAM

Double data rate (DDR) SDRAM memory is an evolutionary design of standard SDRAM in which data is transferred twice as quickly. Instead of doubling the actual clock rate, DDR memory achieves the doubling in performance by transferring twice per transfer cycle: once at the leading (falling) edge and once at the trailing (rising) edge of the cycle. DDR SDRAM uses a new DIMM module design with 184 pins. DDR DIMMs are rated for either PC1600 (200MHz x 8) or PC2100 (266MHz x 8) operation or normally run on 2.5 volts. They are basically an extension of the PC100 and PC133 DIMMs redesigned to support double clocking, where data is sent on each clock transition (twice per cycle) rather than once per cycle as with standard SDRAM.

A typical DDR SD RAM