Re: Request a discrete refresh circuit schematic

["PZ" <skierpaul@yahoo.com>]

72 pin simms would be more difficult since we only have an 8 bit data
bus and 72 pin simms expect a minimum dbus of 16 bits.  I'm not saying
you can't do it, there's a couple ways to implement 72 pin simms on an
8 bit bus, but it'll require some extra logic over the 30pin simms.

- Paul

Ed Eastman wrote:
> 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