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Author Topic: A4000 - motherboard FAST RAM simms  (Read 1336 times)

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Offline alexh

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Offline alexh

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Re: A4000 - motherboard FAST RAM simms
« Reply #1 on: February 26, 2008, 09:27:31 AM »
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Tension wrote:
Does that really make any difference.

Yes. Not a lot but it does. There are many other tweaks that do much more though.

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Tension wrote:
I always thought it didnt increase performance if the access time was quicker...

Eh? By having a shorter DRAM cycle time, you can get more cycles in a fixed time period?

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Tension wrote:
Can a techie explain?? ;)

How in depth shall we go?

The speed rating on a DRAM (RAS) is roughly half a DRAM's minimum cycle time. In the A3000 or A4000, the standard DRAM cycle time is 200ns.  The most recent RAMSEY device (DRAM controller) has a "skip" mode that cuts the standard cycle down to 160ns.  This works with 60ns DRAM and perhaps some 70ns DRAM, and cuts out one "wait state" from all DRAM cycles.

The effects of this speed increase are somewhat reduced when using accelerators which support burst access. (NOTE: A3640 doesnt support burst access)