🚀 go-pugleaf

In article <4781@aplcen.apl.jhu.edu> gotwols@warper.jhuapl.edu (Bruce Gotwols) writes:
>screens if the user writes to the screen while DMA is in progress.  The claim is
>that the act of writing to the screen (on EGA and CGA only) involves using the
>processors Non Maskable Interrupt (NMI), and since the NMI has higher
>priority than DMA it may keep things tied up long enough that the next A/D
>sample comes in before the last one is safely stored in memory.
>
>Can anyone out there confirm that writing to the EGA and VGA screens involves
>using the NMI?  If this is true, under what conditions is the NMI used?  
>(Surely it isn't necessary to invoke the Non Maskable Interrupt just to write a 

I read a Chips & Tech application note that said that they use NMI
to signal a program is writing to video controller addresses and switch
mode modes automatically (It doesn't happen by magic!)