What the difference btw EDO vs SDRAM

[evergreen96]

Is the circuitity difference, power requirements....difference.

I know about the speed issue. 60ns vs 8 ns

Would it be possible to put a SDRAM chip in EDO system? Mainly a laptop w/ 144 pins.

 

[RemyCanad]

I do not belive so. You need all the pins and sence you only have 144 you would be short. And on top of that your chipset would need to know how to use sdram and so on.

 

[AndyHui]

All laptop SODIMMs are 144 pin, regardless of being EDO or SDRAM.

The problem with SDRAM is that it uses a different voltage: 3.3 volts as opposed to EDO which uses 5 volts.

You also need a chipset that will support SDRAM.

 

[RemyCanad]

wooops I wasnt even thinking of a laptop

 

[nightowl]

EDO also is made in 3.3V versions. This applies to EDO DIMMs only. Also, the 440LX chipset supported both EDO and SDRAM.

 

[454Casull]

72 (or was it 68?) pins for a stick of EDO.

 

[Boostretard]

EDO and SDRAM are entirely different standards. SDRAM is supposed to be kept in sync with the CPU (but in modern systems is actually synced with the northbridge) in order to keep track of it's updates.

If I understand what I've read correctly, with EDO you send a request to the ram and it replies when it's ready 70 or so nanoseconds later, then you make your next request. With sdram you send a request and wait 3 clocks and send another request. It still takes 70ns to get the data but every 3 clocks (for cas3) you can make your next request. From a latency perspective it still takes 70ns to get the data, but from a throughput perspective you get a major gain.

Of course I could be wrong.

If you want to look into it more, check out kingston's ulimate memory guide: http://www.kingston.com/tools/umg/umg2000.pdf

- Steve