SDRAM, DIMMs and 100 MHz

A few months ago it seemed that used changes whirlpool in the computer world had calmed down a little, at least as for the memory. Finally it was no too much that to think: to buy approximately 16 ó 32 MB of RAM and, as for the type, undoubtedly EDO. But everything good is finished...

At present, with the massive arrival of Pentium II and the Super badges 7 for AMD K6-2, the type of memory to be bought has changed overnight, and the not one but two times. Now undoubtedly the most advisable thing is to buy DIMMs of 100 MHz SDRAM.

Perhaps it would be convenient to explain this a little for the beginners (and for those who should have committed the error of relaxing; in computer science, a pair of months can turn you into an ignorant troglodyte). Let's start that's why of the "DIMMs".

• The DIMM are modules of memory, small elongated badges where sueldan the chips of RAM (of the type that they are) to handle them more comfortably. The difference of the DIMM opposite to other modules (like the SIMM) is that they are longer (approximately 13 cm opposite to 10,5) and they have more electrical contacts (168 opposite to 72), in addition to two grooves to facilitate his correct laying. It is necessary to emphasize that there exists DIMMs of memory SDRAM or of EDO, since it is only a type of connection.
• The SDRAM is a type of memory very advanced RAM, so much that his refreshment speed is 20 ns or very much minor (opposite to 50 ó 40 of the best EDO). This allows him to work at big speeds without problems, and has made possible the enlargement of the bus of 66 MHz memory to 100 MHz (calm, now we go with this). Due to these advances, only it appears in the shape of modules DIMM, since it is not interesting to the manufacturers to lose time and money in implementing it in the obsolete SIMM.
• 100 MHz refer at the speed of the bus of memory; that is to say, at the speed to which the microprocessor and the RAM communicate. Major all that is this one, much better; for it, Pentium II to 350 and 400 MHz and the AMD K6-2 have raised it from 66 up to 100 MHz, for what memoirs SDRAM are used of: less than 10 ns! Undoubtedly it is something incredible...
  ... And as it, to the being a technology almost in tests and that needs a major precision in the manufacture, the SDRAM chips have to 100 MHz an unpleasant tendency to be incompatible some with others, although this goes getting ready little by little, at least in the memoirs of recognized marks.

The whole of all this can be summed up "in two words": PC100. It is a question of the technical Intel specification for the memory 100 MHz SDRAM, so that he insures himself the memoirs compatibility ("memory" y "compatibility"? It will be a prank!). So he knows already: buy memory PC100.

And is enough the memory PC100? Well, in fact not. It is necessary that the badge is prepared to support it (if not, it has thrown the money), for which it will have to have the chipset BX if it is a badge for Pentium II or to be a badge "Super 7" (one with socket 7, AGP and bus to 100 MHz) if it is a question of an AMD K6-2.

Very well, he knows already. Even if he is going to buy a Pentium at least of 350 MHz or an AMD K6 normally (not the K6-2, also called "K6-3D"), is worth spending him a little more and insuring itself the enlargement of his mike in the future. How, which believes that it will not be worth extending him? Since according to the same Intel, Pentium II has left like a year of life (and that to the models to 450 MHz...).