SIMM, Address Lines Order?

[Allison]

>
>Subject: Re: SIMM, Address Lines Order?
>   From: Scott Stevens <chenmel at earthlink.net>
>   Date: Mon, 26 Sep 2005 18:24:22 -0500
>     To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org>
>
>On Mon, 26 Sep 2005 10:35:16 -0400
>Allison <ajp166 at bellatlantic.net> wrote:
>
>> Tim Olmstead wrote a Z80 Dram interfacing manual thats around the net
>> and cover simms as well as the ram on them. Very useful.  I have an 
>> electronic copy locally if needed. 
>> 
>
>The Z80 has DRAM refresh functionality built right into the processor,
>if I'm remembering right.

You remember right but there was a gotcha.  the Z80 refresh was only 7bits
and about half the 64k drams requried a 256 (8bit) refresh.   the solution 
was with later parts you could do cas/ only refresh and that used the Drams
(later parts and those used for simms) internal counter for refresh address.


Allison