Request a discrete refresh circuit schematic

[Ed Eastman <noone@nowhere.net>]

Since there is no A2 hardware forum, I'll post it here...  (Sorry about 
posting to the emulators group.)

I need a circuit to refresh some stand alone ram for a RAM expansion 
circuit I am designing.  (12M Ram on the IIgs)  I understand the basic 
theory but I need an actual circuit with real RAM chips to help me 
visualize the process. I've looked on the internet but the refresh 
circuit is always glossed over and people are using a memory manger or 
some such chip that I don't have access to.

Would someone please send me a discrete schematic of a refresh circuit 
on say, a 4 meg bank of RAM?  Or I'd be just as happy with a point to 
some resources readily available via internet or book reference.

I forgot to mention I'd like to use some old 8bit SIMMs I have laying 
around.  Of course the circuit would be just as easy on a 72 pin simm.

Thanxk,
Ed
eeastmanNO@SPAMgmail.com