Re: An FPGA card for Apple

[alex.freed.007@gmail.com]

On Jan 18, 8:12 am, MdntTrain <j...@cimmeri.com> wrote:
>
> If 14MHz were on the bus, would you then be able to use the Cyclone
> II?

Yes, in theory. In practice that would mean re-doing the whole thing
from
scratch. If anyone wants to make another board with  a Cyclone II
chip,
it's fine with me. I'll be glad to help with advice if needed, but we
are not
likely to change the current design.

BTW as I already said Steve Howell is the one who does 99% of this
board design work.

>   If in that case, you could, then in reality, is there no way to
> tap the 14MHz off some IC?

That would be ugly. A frequency doubler external to the FPGA would
have been a better solution.
In fact you can even put an independent clock generator on the board.
It doesn't have to be synchronous with the Apple clock but it helps to
keep it simple and avoid unpleasant issues like metastability.

>
> I imagine it'd be very difficult to change FPGAs at this stage in the

exaclty

> game, but from a hobbyist perspective, having the same FPGA as your
> FPGApple DE1 and Stephen Edwards Apple2FPGA, and being able to use the
> better Quartus tools, is very attractive.     But never having done
> anything with FPGAs, this is just speculation on my part.

The project is all portable Verilog and uses no vendor specific
primitives. So it
doesn't matter too much. I prefer Altera tools myself except for some
special
cases, but I'm not religious about it.

Just like I prefer *NIX but if some program I need is written for
Windows, I'll use
Windows.

-Alex.