Date   : Sun, 11 Jan 2004 20:51:10 +0000 (GMT)
From   : Sprow <info@...>
Subject: Re: NMI Handlong on the Electron

In article <20031104091336.00AC.CHRIS.JOHNS@...>,
   Chris Johns <chris.johns@...> wrote:
>  I've made some progress with the Electron Econet project, I've managed
> to talk to a fileserver, and *Stations from my RiscPC now includes  "127
> Acorn Electron" - however I've been bitten ny the NMI handling in MODEs 
> 0-3.
>
> As I understand it, when the NMI occurs, it steals the CPU from the ULA,
> and causes the ULA to stop accessing the RAM - giving the "snow" effect.
>
> When you've finished handling the NMI, you're meant to set the NMI clear
> bit (bit 7 of &FE05) which tells the ULA it can have the RAM back.
>
> Anyone any ideas?

Try JMP &FFAC instead, this is special Electron NMI exit code,
Sprow.