Hi

> I wonder if it would be very complex to create a board similar
> to the old X-Calibur board for A3640, that plugged between the 040
> and the A3640 and contained 128MB (soldered).
> There are thousands of A3640 boards out there that are almost
> useless because you can't fit more than 16MB in the motherboard.

Could it be done, yeah. Xilinx give the code away for Dram and SDRam
controllers for use with their CPLD's, but honestly it aint worth it
imho. (unless a cheap adaptor for the A2000/A500 could be made that
would use the low end fast slot cards, which you could maybe build
the memory controller on too)

> I guess that with a small FPGA that acted as memory controller
> for the 040 and a pair of 64MB DDR memory chips it would be enough.
Argh DDR, noooooo.
Come on, 72 pin simms are easy to add, there are the designs on
aminet for adding 8 meg of ram to an A500, the design would only need
a minor change to fit directly on an 040 bus.
SD-Ram would be ok too, but nooooooo not ddr. :) (yeah I know you
will come back with "but you cant get simms and sdram any more", I
just ordered 128meg of brand new 72pin simms (60ns) and it cost me
£20, every computer shop in the UK seems to still stock 72pin simms,
even the one up the road from me)

A new 68060 card would be much better and with the price of PCB's and
CPLD's/FGA's falling all the time you could probably make a very
cheap 060 card, the fast slot connector would be the biggest expense.
Even second-hand 060's are cheap from ebay. (And there are ways round
the rohs system so you could sell a new 060 card thats rohs compliant
and just have a plug in second hand 060 chip)
Anyway thats going off topic rather fast.

The answer is yes it can be done, the code is availble for some
generic memory controllers like as you say opencores and xilinx.
I have no idea what the price would be like, say £55-ish retail maybe.