Sunday, March 1, 1998
CAN'T TELL WHAT TYPE OF MODULE IT IS?
There are just too many look-a-like memory modules floating around. With so many copycats out there, sometimes it takes an expert to figure out if a module is truly marked correctly.
The Electronic Industry Standard Committee(JEDEC) has just standardized a way to distinguish module types. It is called the "Serial PD" method.
The Serial PD method involves adding a serial access Eprom or EE-prom device on each module. The device is electronically engraved with information like address capacity, data width, fundamental memory type (Page mode, EDO, or SDRAM), refresh lines, refresh period, and operating voltage. Since this is a serial device, it occupies very little real estate on the module and only requires two line connections - one for the clock "SCL" and one for the bi-directional data line "SDA."
In the very near future, these "Serial PD" modules will surface on the market and soon become the standard. If so, this will challenge Module tester manufacturers to provide serial PD programming capability to module manufacturers. And on the other hand, also provide a tester to the dealers and end-users to read out and interpret the serial PD information now programmed in each module
By: Cecil Ho
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