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Calculator Community => TI Calculators => General Calculator Help => Topic started by: Hot_Dog on April 14, 2011, 02:07:07 pm

Title: Memory Refresh?
Post by: Hot_Dog 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?

Title: Re: Memory Refresh?
Post by: Stefan Bauwens on April 14, 2011, 02:11:19 pm

I guess it after a time just gets full with stuff.

Title: Re: Memory Refresh?
Post by: Runer112 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.

Title: Re: Memory Refresh?
Post by: ztrumpet on April 14, 2011, 05:01:46 pm

When does this Memory Refresh normally happen?

Title: Re: Memory Refresh?
Post by: Hot_Dog 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.

Title: Re: Memory Refresh?
Post by: willrandship 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.