On Feb 1, 9:33=A0am, Alex Freed  wrote:

> I guess one option could be a modified PD8 that would override the $F8
> ROM (like a ROM card does) and point a reset vector to its own code.

Seems to me there's two problems: on-the-fly switching and boot-time
switching.

On-the-fly could be handled by a switch that triggered NMI - you can
see the NMI and the card and activate your own firmware in $Dxxx-$fxxx
using /INH. the firwmare could then select another image.

For boot time, a simple timer could be reset by an access to $C6xx

I envisage a system where images are grouped into 'sets' by being
placed in a directory (perhaps with a .dsks extension). Hitting the
switch during 'play' simply causes the next image in the set to be
swapped in, and control returned to the system. At boot time you
choose either an image or a set, depending on your preferences.

Matt
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