Hi Matt,

my English is not so good to understand
all the fine print of the last babble.

But let us return to your question.
How many RAM need you and how many want you ?

Up to 1MByte I would prefer the using of
2 SRAM devices with 512kB.


On using DRAM:

The Z80 suggestion sounds not easy, since if I
remember right, the hardest things on such a design
was to find out the right values of the 2 caps for
the RAS and CAS delay.

A better solutions sounds to use a CPLD like the
CoolRunner. Especially if data must be read and
write sequencially.

There are a lot of advantages of it:

1.
The timing was not critical, since all the time of
the program fetches until the next MOVX can
be used to complete write or
preread from the following address.

2.
Write and read can be done faster with implementing
an auto increment or also 2 separate read and write
address counters.

3.
The refresh can be done fully in the CPLD e.g. with the
ALE clock signal.

4.
Only some XDATA adresses occupied for setting the address
(e.g 3 Byte) and read / write data.
No Banking needed.


Regards,
Peter