Hi Jay
Yes, if we could get the TMS70C02 to work with some custom CTS256 firmware that would solve the limited availability of hardware issue. TMS70C02 are really common and inexpensive.

TMS7001, TMS7041, PIC7001, PIC7041, I think they all work fine but aren't nearly as common as TMS70C02. I think TMS77C82 would be even better yet although would require more extensive changes.

Thanks, Andrew Lynch