The J-CIA is an FPGA-based replacement for the MOS 6526 and 8521 CIA chips used in Commodore computers. It has been tested and found to be compatible with various hardware and software, including demos and games. The J-CIA is about the same size as the original CIAs and can be installed using IC sockets, although caution is needed to avoid damaging the pins. There is an option to switch between the new 8521 mode and the old 6526 mode. It should be noted that the J-CIA is not compatible with Amiga/8520 CIA and cannot be later converted or upgraded. There may be some differences in functionality compared to the original CIA, but the aim is to recreate the logic as closely as possible. The J-CIA is available for purchase from various online shops. Finnish customers can buy from Am-Mek, while international buyers can choose from Run Stop Re-Store and Retrospective shop.
https://1nt3r.net/j-cia/