Dynamic ram refresh is in all the Z80 flavor s (Z80, Z180,Z280...).
I have a paper done by Tim Olmstead on how to use refresh and
make it work.? ?I'll have to put that in the files area.
FYI the worst example of its use were some S100 memory cards
and the early TRS80 console. All cases it was trying to either
attempting to cheap out or lack of understanding of Drams and
also Z80.? ?These days Static Ram in the 32k (61256) or 64K (61512)
sizes is the end all solution.? That is especially true when using the
faster than 4mhz z80s.
