Re: Softcard: DEVSEL instead of IOSEL possible?

[mdj <mdj.mdj@gmail.com>]

On Nov 23, 12:07 pm, Linards Ticmanis <ticma...@gmx.de> wrote:
> Has anybody ever tried making the CP/M Softcard use DEVSEL $C0nX instead
> of IOSEL $CnXX for CPU switching, by rerouting that trace? If I
> understand things correctly, this should enable using the card in slot 3
> (the only one free in my crammed IIe) with a patched CP/M. As the
> Softcard doesn't really need ROM space I think this would be easily
> possible.
>
> Of course the "slot scanning" code used to find the card would have to
> go away (rather than merely be modified), as randomly accessing DEVSEL
> space is probably a very bad idea. But the slot 3 location could simply
> be hard-coded into the patched CP/M.
>
> Or am I completely on the wrong track here?

It should work fine. As you point out you'll need to defeat the detect
code and patch the select code accordingly, but I see no reason why it
won't work.

I usually just pull my mouse card when I need a z80 board, since I've
never had call for interrupts in z80 mode. A good alternative though
in your case might be to use one of James Littlejohns slot switchers ?

Matt