memory modul
Memory bars, also known as memory modules, are small circuit boards on which the memory components for the main memory are located. They are equipped with a contact strip and are plugged into the designated slots on the motherboard. The slots are located directly above the memory bus to which they are connected.
There are two different versions of the basic concept: Single Inline Memory Modules( SIMM), which are no longer supported in personalcomputers(PCs), and their successors the PS/2 modules, and the Dual Inline Memory Modules( DIMM). The DIMM modules differ in structure and contact strip depending on the memory chips used and their architecture. Therefore, there are DIMMs with 168 and 184 pins for Synchronous Dynamic RAMs( SDRAM) and with 240 pins for DDR2. There are also special DIMM modules for Rambus technologies: RIMM for Rambus Dynamic RAMs( RDRAM) and XDIMM for Extreme Data Rate DRAMs( XDR- DRAM).
In order to prevent accidental insertion of a DIMM module into a slot not intended for this purpose, the contact strips also have a notch located in different places.
The assembly of a memory bar with memory modules depends on the number of data signal lines of the memory chips and the data bus. For PC main memory, memory chips with 4, 8 or 16 data signal lines are permitted. A memory block for 64 data lines can thus be built up from sixteen memory chips with four data lines or from eight memory chips with eight data lines or from four memory chips with sixteen data lines.