>I have tried operation in DOS windows, full screen DOS box, and >completely exiting windows down to DOS. Same results. >> All I can suggest is to set up a dual boot system to boot to DOS6.22. I had a similar problem running the Parallax programmer from the DOS window in Win3.1. If I just used plain old DOS it worked fine. Tony For the beginner.... PicNPoke Multimedia 16F84 Simulator Assembler, and Tutorial. Now with PicNPlay circuit simulator. Plus animated Address Mode Tutor. http://www.dontronics.com/picnpoke.html