[Coco] MPI (Gene Heskett)

[Mike Pepe]

Andrew wrote:
>  >> This does not bypass the slot switching of the scs signal, so it
>  >> should still work when you power up the system with a game in the
>  >> slot the switch is set to.
> 
> Gene, Arthur:
> 
> Since you both responded in nearly identical ways, I just wanted to 
> clarify what I was meaning by having a bunch of cartridges for my MPI.
> 
> I got my MPI as a child, and I know I have the upgrade to use it with my 
> CoCo 3 (had it on my CoCo 2 before I got my CoCo 3 as a kid).
> 
> I guess what I would like to make sure of is that even with those 
> signals tied (after the mod for OS-9) if I could still (for instance), 
> plug in my Disk Controller, RS-232 Pak, Speech/Sound Cartridge, and 
> Orch-90 Pak - and use them all under DECB.
> 
> So - could I set the switch to the Disk Controller, boot up in DECB, 
> then load UltimaTerm (or another comm program), and dial out a modem via 
> the RS-232 Pak? Or, alternatively, load up Gauntlet, and it would be 
> able to "see" and use the Speech/Sound Cart for voice output (I think 
> that Diecom game uses it)?
> 
> I am not sure DECB or any programs under DECB care about those 
> particular interrupts, but I just wanted to make sure it would still 
> work - or if the modification would need a switch or something to allow 
> the user (me) to "untie" those lines if I wanted to used DECB instead...
> 
> -- Andrew
> 

Agreed. Keep in mind, those IRQ interrupts would/could be used under a 
non-OS9 terminal program. However, it should not be an issue when used 
in that way.

I also don't believe that strapping the IRQs on a MPI would affect 
anything outside of OS9 either. The disk controller doesn't use the IRQ. 
  The orch90 doesn't. No program paks do either. Not sure about the S/S 
pak. The only one I'm aware of that does at the moment is the RS232 pak.

Also somewhere out there is another mod that fixes an issue where a 
character that is being assembled is discarded when a particular line on 
the 6551 is de-asserted. Again, probably not an issue for casual usage. 
I think Sockmaster's site had that mod. I just thought I'd mention that.

-Mike