SRAM vs SDRAM

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originally posted by smcnutt@Jan 20 2005, 01:29 PM

hi cetic,

> ... i have read in some threads around here that sdram performances

> were quite bad.

i've found the sdram controller performance to be pretty awful. given

the logic area it occupies and its performance, i no longer consider it a

viable alternative for many new designs.

> sram is a bit expensive if i want to have enough memory to run

> my linux (i guess i need at least 4mb).

i've switched to psram (pseudo sram) for new designs. it eliminates

the sdram controller and it performs better[/b]. The cost is

very attractive ... the expense is the number of pins you must use.

Regards,

--Scott

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[/b]

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Scott,

I&#39;ve been consdering using PSRAM for our upcoming NIOS II system, mainly due to it&#39;s much lower power consumption vs DDR.

Do you use the PSRAM as a simple SRAM replacement (in which mode it has quite slow 70ns access times) or do you make use of the Burst mode to get much faster average access rates?

I&#39;ve been tinking about knocking up an interface block to access it in burst mode but the effectiveness of that depends on whether the NIOS can cache grabs it&#39;s instruction stream in bursts or not.

Mark.