Re: C128 and 8MHz Z80 (revisited)

On Thu, Jun 6, 2024 at 5:48 AM Jim Brain <brain_at_jbrain.com> wrote:

> If you are using Linux, it should be easy (Xilinx WebPack ISE dload).  If
> using Windows 10/11, shoot me a personal email, as it's not tough, but it
> requires replacing a DLL to get it to work.
>
Not a problem, I use daily both, but I'm leaning back towards Linux after a
long break (even though half of the Linux time is WSL).


> WIth the 72 pin CPLD (of which I have a ton, no supply worries there), it
> uses 10 or so pins, 1 flip flop, and 4 macro cells.  I thought about
> pushing more signals into the CPLD, but I thought I'd wait to see what is
> interesting, as I barely know the Z80 bus.  But, you could easily pull in
> all the non Address/Data signals, and with a bit of layout, you can pull
> all the address and data lines in (put the speed under SW control, if
> desired).  I also need to add in a third clock source, which is a PLL that
> runs off the dot cock but multiplies the dot clock (with low skew):
>
> Datasheet:  https://www.renesas.com/us/en/document/dst/501-datasheet
>
> By default, it doubles the input clock, but can do 2x,3x,4x,5x,6x,and 8x,
> and also some factions.
>
> (...)
>
> I was thinking the same, so I'd recommend adding in a lot of the signals
> you'd like to play with, and then you can wire them up in the CPLD and see
> what works best.
>
> Adding in on board RAM is also possible, and using a few register bits to
> denote what parts of Z80 RAM you wish to mirror, if any.
>
> I forked your github project and added my stuff into it my version:
>
> https://github.com/go4retro/C128-Z80Plus
>

Thanks a lot for your work and advice! That is more than I could wish for
and will keep me busy for a while.
I'm super excited to try it out.

ytm