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Author Topic: Memory Refresh?  (Read 4574 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?
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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.
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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?
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Offline Hot_Dog

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Re: Memory Refresh?
« Reply #4 on: April 14, 2011, 05:44:17 pm »
Quote from: ztrumpet on April 14, 2011, 05:01:46 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.
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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.
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