Hi Bill I don't have one handy but you need to state how your SIO card is configured. The one I have, has a number of jumper options. I think we'd need to know the options for which bits are used for which. Dwight ________________________________ From: Bill Degnan via cctalk <cctalk(a)classiccmp.org> Sent: Sunday, July 23, 2023 6:52 AM To: General Discussion: On-Topic and Off-Topic Posts <cctalk(a)classiccmp.org> Cc: Bill Degnan <billdegnan(a)gmail.com> Subject: [cctalk] IMSAI SIO 8080 Comm Program? I am looking for a basic or commercial IMSAI SIO 8080 Comm Program that uses SIO serial connector 2 for modem communications. Something I can start from a ROM monitor running from the console running through serial connector 1. My system is using the original 8080, I want to avoid the cp/m z80 route. Bill