Author Topic: Memory Refresh?  (Read 3548 times)

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Offline Hot_Dog

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Memory Refresh?
« on: April 14, 2011, 02:07:07 pm »
I understand what memory refreshing is, but why does memory need to be refreshed?  Is it because memory will sooner or later lose its contents, or is there another reason?

Offline Stefan Bauwens

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Re: Memory Refresh?
« Reply #1 on: April 14, 2011, 02:11:19 pm »
I guess it after a time just gets full with stuff.


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Offline Runer112

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Re: Memory Refresh?
« Reply #2 on: April 14, 2011, 04:21:55 pm »
The capacitors that hold the bits of data in RAM don't perfectly hold a charge, so they must periodically be "refreshed." During each refresh, any capacitors that are holding charge are topped up and any capacitors that are not are left empty.

Offline ztrumpet

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Re: Memory Refresh?
« Reply #3 on: April 14, 2011, 05:01:46 pm »
When does this Memory Refresh normally happen?

Offline Hot_Dog

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Re: Memory Refresh?
« Reply #4 on: April 14, 2011, 05:44:17 pm »
When does this Memory Refresh normally happen?

Sometimes after each instruction, other times after a certain number of instructions.  On the z80 processor, it happens about every 64-128 instructions.

Offline willrandship

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Re: Memory Refresh?
« Reply #5 on: April 14, 2011, 05:46:48 pm »
I know my homemade memory only needs to be refreshed after 20 minutes or so, but then that's with a 1 uf cap, so it prob. needs it much more in the ICs. Most mem doesn't use caps, tho, that's odd. two transistors work far nicer, for binary anyways.