• Memory modules control how fast data transfers to CPU can take place.memory image by Zbigniew Nowak from Fotolia.com
  
  DIMM is short for dual inline memory module, and SIMM for single inline memory module. There is a connection between the pins that are on the lower edge of the front and back parts of a SIMM. This provides a single line of communication between the module and the system. On a DIMM, however, the pins are not connected. They provide two lines of communication between the module and the system; one lies in the front and one in the back.
  
  

Popularity of DIMMS

• DIMMs have replaced SIMMs and are the defacto memory module on motherboards.computer mainboard image by starush from Fotolia.com
  
  DIMMs have all but replaced SIMMs in computers today. Apparently the only place that you would probably see SIMMs would be on older computer motherboards. DIMMS can hold more data than SIMMS, almost twice as much. Memory, either in SIMMS or DIMMS format, works with the CPU. The CPU receives data to process from the type of memory module in the motherboard.
  
  DIMMs have become so dominant in computers that it is not necessary to identify the memory module as a DIMM or SIMM. There are no replacements to DIMMs modules at the moment. The current memory technology depends on the design of motherboards and what the specifications are. Hence, motherboard manufacturers as well as CPU designers will be dictating the future design and replacement of the DIMM.
  
  It is not unreasonable to think that these memory modules will still be manufactured for the foreseeable future.
  
  

Backwards Compatibility

• DIMMs are not backwards compatible to SIMMs.memory image by Valentin Mosichev from Fotolia.com
  
  DIMMs are not backward compatible with SIMMs, so it is not possible to simply upgrade the memory modules. SIMMs have a 32-bit (1's and 0's) data path and only 72 pins; it is necessary to install pairs of modules. DIMMs have separate electrical contacts on each side, not like SIMM's which are redundant contacts. DIMMs have a 64-bit data path. They can be installed individually in the socket, that is, only one is necessary; pairs are not needed. The number of pins on a DIMM depends on the type of DIMM.
  
  Moving from SIMMs to DIMMs was not easy because it required a replacement of the motherboard which also meant the replacement of the processor. This explains why the change to DIMMs was not quick; most people opted to switch to DIMMs when it was necessary to upgrade or replace the entire computer.
  
  

Bus Size

• DIMMs use a larger bus size which allows them process more data.memory chips image by Jack Kunnen from Fotolia.com
  
  The processing advantage comes when you operate with a much wider data bus that a DIMM can utilize. A bus is a series of connections between memory and the CPU. DIMMs are 64 bit modules compared to the 32 bit modules used by SIMMs. A wider bus means more data is available for processing. This, in turn, means an overall faster performance. The reason is that more data going through the bus allows the CPU to work with data without having to wait.
  
  Working with a 64 bit bus is not the exclusive domain of DIMMs. SIMMS also achieved this capability. The process is to use two SIMMs in tandem. This results in having a bus operate as if it were two buses. However, DIMMs have made this practice unnecessary.