08-13-2023, 12:59 PM
Testing the ports will probably be the answer. From the old BASIC-80 manual for the CP/M version of Microsoft BASIC, the INP command limited you to only 256 ports, which would not work on an IBM PC. But GW-BASIC and BASICA allow for reading up to 65,536 ports. I will need to dig through the Dual Async Adapter/A Tech Ref to find out what ports I need to query to see if there is data available.