[vcf-midatlantic] Debugging with NMI on the PC

[Richard Cini]

Thanks Garrett. I have my NMI button ready to go. The Gazelle is a non-PC compatible without byte-addressable video (character TTY only) so many debuggers won't work because of the graphics. It's such a hassle finding stuff that works on this machine because of the video limitations.

Rich
 
--
Rich Cini
http://www.classiccmp.org/cini
http://www.classiccmp.org/altair32
 

On 6/10/20, 7:46 PM, "Garrett Nievin" <gnievin at silvaire.org> wrote:

    Programming the strange "high res" adapter (two full-length boards with
    a jumper cable, something like 640x400x16) on my Sperry PC back in the
    day, I just soldered in a switch that connected NMI to ground and used
    it with basic tools like Borland Turbo Debugger.
    
    http://www.bitsavers.org/pdf/borland/turbo_assembler/Turbo_Debugger_2.0_Users_Guide_1990.pdf
    
    I'd be running graphics code on the "high res" adapter, and have an MDA
    card with debugger running on the monochrome display.
    
    Cheers,
    Garrett
    
    
    
    On Wed, 10 Jun 2020 19:13:14 -0400
    Richard Cini via vcf-midatlantic <vcf-midatlantic at lists.vcfed.org> wrote:
    
    > 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
    > 
    >  
    > 
    > --
    > 
    > Rich Cini
    > 
    > http://www.classiccmp.org/cini
    > 
    > http://www.classiccmp.org/altair32
    > 
    >  
    >