No, CAS goes low then high, RAS remains unasserted. Some memories allow
you do keep CAS low and cycle the address bits through a page without
deasserting CAS. Some do the cycling themselves after you assert CAS
alone, or otherwise. Get the data sheet. Most do auto refresh on access,
i.e. it's enough to read a whole page normally from time to time to
refresh it. Just don't use the data and you can shorten the cycle usually.
Get the data sheet anyway ;-).

Peter

On Wed, 1 May 2002, Tony Nixon wrote:

>Hi all,
>
>Has anyone got some knowledge of CAS before RAS refresh?
>
>Does CAS go LOW, then RAS gets cycled for each ROM address, then CAS
>goes HIGH again?
>
>I have a 4 Meg X 9 30 pin SIMM hooked up to a 16F877 and while it
>appears to work, I don't know if the refresh is correct.
>
>
>--
>Best regards
>
>Tony
>
>mICros
>http://www.bubblesoftonline.com
>mailto:sales@bubblesoftonline.com
>
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>
>

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