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  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

im looking for a simple 8 bit dram refresh circuit

777xxx

Member
i have some 4164 dram chips and i want to build a refresh circuit for them. ive tried looking on google but cant seem to find anything understandable. any help would be appreciated.
 
You use an 8 bit counter gated to the address pins, pulse /RAS low at regular intervals between normal access cycles. It needs to cycle through all 256 addresses every 4mS or less.
 
@OP, I resurrected 1103's some years back mainly as a challenge due to the complex seriously ugly timing.

Quite instructive an a great rainy day activity. I have some 2900 bit slice and Signetics
8X300 parts I want to tackle at some point as well.

Good luck with your effort.
 
Years ago, I had the CPU refresh every 1mS. Set up an interrupt for the timing. I think I did 256 sequential reads as fast as possible. Don't remember the details.
 
The only ones I've built myself were for an old MC6809 system.

That CPU uses quadrature clocks (E & Q) and only access memory during E high.
I use E low & rising edge of Q to trigger a refresh then increment the counter.

(I had 1MB of dynamic RAM on that system).
 

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