RAM in the first models of serial computers was an integral part of the entire system. Perhaps someone else remembers the 80286 processors and motherboards for them.
In the first audits, a hugethe number of soldered small connectors into which the chips were inserted. Added such a chip - got a few kilobytes of RAM, although, as a rule, no one was building up the volume. Usually the system was bought immediately with a certain amount of memory. And the price of chips was quite high. However, with the development of semiconductor chip manufacturing technology, the cost of components began to fall (this process continues in our time), and it became necessary to create a universal solution that allows you to increase the amount of RAM without special problems. So the memory module was created (now you can hear the slang expression - the bar). Since then, several decades have passed: standards have been replaced, microchips have been improved, but the idea itself has remained unchanged.
What does the memory module look like?
Distinguish the bar from other components very muchsimply: it is a rectangular plate of textolite, on which chips are soldered on one or both sides. The memory module can be closed with a metal radiator, which improves heat dissipation. For connection to the motherboard there is a comb of copper sliding contacts. The first such solutions began to be called SIMM, which stands for "Single In Line Memory Module", that is, "memory placed along one line." To fix them on the board, special connectors were created, in which each memory module was inserted at an angle of 30 degrees, and then it straightened out, being fixed.
History of the development of laths
The first SIMMs contained only 30 contactsites, could boast a volume of up to 2 MB and ... an 8-bit bit capacity, which caused them to be installed in pairs in order to match the system bus. The development of the famous Pentium processor with a fantastic 32 bit capacity for that time required the modernization of the memory subsystem - the slats got 72 contacts.
Then, before 1997, there were no cardinalno changes were made. The volume of microcircuits increased, no more. But soon a new standard was created - DIMM, which stands for "Dual In Line Memory Module". In these modules, copper contacts appeared on the second side, and their number was increased to 84 pieces per side. In addition, the bit capacity has increased to 64 bits. By the way, the modern DDR2 memory module is also 64-bit (for the usual single-channel mode).
Evolution of DIMMs
After a while, the SPD chip was placed on the slats,which contained data on the capabilities of microcircuits - this simplified the autoconfiguration. The appearance of modules with a reduced supply voltage forced the developers to create a special "key" - a cutout in the contact block, thanks to which the old types of straps (with greater strain) were physically incompatible with the new ones. The frequencies grew, the amount of memory increased. The contact was 184. A memory module was created for the laptop - from the usual it differs in design, allowing to place several such solutions in a small case of a laptop computer. To improve performance, it was suggested to transfer data in an accelerated mode - so there were DDR slots, in which the signal is transmitted more optimally. Then, DDR2 emerged, with reduced voltage and an even more dense use of the carrier frequency. At present, modern computer systems use DDR3.
