[vcf-midatlantic] Debugging with NMI on the PC

Richard Cini rich.cini at gmail.com
Wed Jun 10 19:13:14 EDT 2020

All –


                I’m working on an S100 project with my Gazelle (a VGA board) which is based on a standard Trident VGA chip. The BIOS on the video board relies on a PC BIOS (which doesn’t exist for the Gazelle) so I’ve had to hack something together for it to make it work. The BIOS is barfing somewhere in the initialization, but it’s a hard crash so resetting it to regain control destroys the context. I’m running under MSDOS 2.01.


                I remember that there were debuggers like Periscope or SoftICE that could trap NMI, but I need it to be pure character-based like MS-DOS debug.  Does anyone know of any debuggers like this? There was one by Paul Vojta, which I have the code for, but that doesn’t trap NMI. I wonder if I could just have the NMI call INT 03H (debug break) since they all trap that.


Any thoughts or help appreciated. Thanks!





Rich Cini




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