SRAM and DRAM demonstration using relays

[John Newport]

My thanks to all who helped me with my previous problem about demonstrating the operation of logic gates using relays.

I have another, similar, question that I would appreciate help with.

Is it possible to demonstrate SRAM and DRAM using relays and indicator lights?

I may be asking the impossible as I have no idea about this at all.

A second question, please, is, where can I find the simplest and clearest description of the above items, as I’d like to educate myself but most description I’ve seen, seem to assume more knowledge than I’ve got!

Thanks in advance.

John

 

[Ian Rogers]

You can use the flip flop action... I can do SRAM but DRAM is superfluous as there is no need to dynamically update it!!

You just use relay one to latch the second and the first can release the latch...

 

[John Newport]

Thanks Ian,

Yes, I see - I now remember a straight forward latching flip-flop but it has been more years than I care to think about! It's strange how it all seems so obvious when someone tells you how! Why didn't I see it the first time?

And I understand about the DRAM.

Sorry, my friend, for showing my ignorance - and thank you for your help.

Cheers,

John

 

[ronsimpson]

A SRAM is much like a SR-FF or your two relays.

A DRAM is simple. It is more like a very large capacitor across the coil of a single relay. When you write to the RAM you take the voltage on the capacitor to 0V or 5V for a (0 or 1) and the capacitor stores energy for a short time. It will keep the relay on or off for 1mS. DRAMS must be rewritten every 1mS or they forget. So every 1mS you must read the relay and rewrite the information back into the capacitor.

The point of the DRAM "D=dynamic" is it used only one relay not two. Half as many parts. But it must be used all the time.

 

[John Newport]

Ok Ron,

Got it. Understand. Again, obvious when told!

Thanks, I'm very grateful,

John