[Coco] Of Multi Pak Interfaces...

[RETRO Innovations]

On 3/25/2015 5:16 AM, Arthur Flexser wrote:
> Out of curiosity, what would happen if you plugged one multipack into
> another, or more gracefully accomplished the equivalent through a
> connecting ribbon cable?  Could one get 7 slots that way, perhaps via some
> minor modifications to the circuitry?
You'd have the equivalent of a 4 port USB hub connected to one port of 
another 4 port USB hub.  When that particular slot was selected, you'd 
get access to 4 ports.

But...

It would be unsusable as is, since the $ff7f config register is shared.  
So, you'd never see more than 1 of the ports on the second MPI.  If you 
plug he second MPI into slot 3 of the initial MPI, only slot 3 would 
ever be active on the second MPI.

Now...

If you use a Y-cable to connect two MPis to one port, you'd be closer to 
working, but still no cigar.  The data bus buffer on the one MPI would 
conflict with the second MPI buffer during read accesses.

I am not sure how you would address that second issue.

>
> Relatedly, how do 3rd party MPIs with more than 4 slots do slot selection?
> Is bit 2, in addition to bits 0-1 of $FF7F, used?
I think others answered this, correct?

Jim