CompuServe Thread

David: Craig Sharp suggested I contact you about a problem I am having. My objective is to write and run C programs in real mode. I can start AutoCAD, xload pwedge, and rload my program with no problems. However, when I try to run my program, I either get an "Abnormal program termination: Illegal instruction" message, or the machine hangs, or it reboots(!). I am using AutoCAD v11c2 386 and SDK 2.0. I have tried using no memory manager, HIMEM.SYS, HIMEM.SYS & EMM386.EXE, QEMM386.SYS; DOS 5.0, DOS 3.30; Phar Lap extender 2.2d and 2.6. I have upgraded the system BIOS. I have run memory diagnostics continuously overnight. I have run diagnostics on the CPU and FPU. I have reconfigured AutoCAD to use only internal VGA and Summagraphics drivers (I usually use ADI drivers; in the case of the display, protected mode ADI). Nothing improves the situation, although some combinations do make things worse – a lot worse. AutoCAD with the Phar Lap extender 2.6 won't even load – the "Abnormal program termination" message shows up before the AutoCAD main menu. This leads me to suspect a problem in mode switching. Phar Lap 2.6 loads itself into extended memory whereas 2.2d didn't; I assume that it must do some mode switching to achieve this. Pwedge mediates between protected and real mode, again requiring mode switching. The machine is an AST Premium 386/25 with 4Mb. I've spent hours on the phone with AST, Phar Lap, Quarterdeck, Autodesk Developer support – no luck so far. Any suggestions? Gary Fraser