Memory slots

Memory slots refer to the type and number of memory slots used on the motherboard. The types and capacities of memory supported by the motherboard are determined by the memory slots. Currently, the main memory slots used on the motherboard are:

SIMM (Single Inline Memory Module)

168-pin SIMM socket

The memory stick is connected to the motherboard through gold fingers, and there are gold fingers on both sides of the memory stick. Gold fingers can provide different signals on both sides, or they can provide the same signal. SIMM is a memory structure in which the gold fingers on both sides provide the same signal. It is mostly used in early FPM and EDD DRAM. Initially, it could only transmit 8bif data at a time. Later, 16-bit and 32-bit SIMM modules were gradually developed. Among them, 8-bit and 16-bit SIMMs use 30-pin interfaces, and 32-bit uses 72-pin interfaces. After the development of memory entered the SDRAM era, SIMM was gradually replaced by DIMM technology.

DIMM

184-pin DIMM socket

DIMM is quite similar to SIMM, the only difference is that the two ends of the gold finger of DIMM are not interoperable like SIMM, they transmit signals independently, so they can meet the transmission needs of more data signals. Although both use DIMM, the interface of SDRAM and DDR memory is slightly different. SDRAM DIMM is a 168-pin DIMM structure, with 84 pins on each side of the gold finger. There are two slots on the gold finger to prevent the memory from being inserted into the slot in reverse and causing burning; DDR DIMM uses a 184-pin DIMM structure, with 92 pins on each side of the gold finger, and only one slot on the gold finger. The difference in the number of slots is the most obvious difference between the two. DDR2 DIMM is a 240-pin DIMM structure with 120 pins on each side of the gold finger. Like DDR DIMM, there is only one slot on the gold finger, but the position of the slot is slightly different from that of DDR DIMM. Therefore, DDR memory cannot be inserted into DDR2 DIMM, and similarly, DDR2 memory cannot be inserted into DDR DIMM. Therefore, on some motherboards that have both DDR DIMM and DDR2 DIMM, there will be no problem of inserting the memory into the wrong slot.

240-pin DDR2 DIMM socket

RIMM
RIMM is the interface type used by RDRAM memory produced by Rambus. The size of RIMM memory is similar to DIMM, and the gold finger is also double-sided. RIMM also has 184 pins, and there are two close-together slots in the middle of the gold finger. The non-ECC version of RIMM has a data width of 16 bits, while the ECC version is 18 bits wide. Due to the high price of RDRAM memory, this type of memory is rarely seen in the DIY market, and the RIMM interface is also rare.