i decided to make a gameboy like gcp and about the extrernal, can i just use the difrent controller slots? becuase on some games i'd need to plug in my gameboy (already own connector)
mmm, not sure what you mean.
anyway, if you keep some controller external ports at the system you will be able to plug another controllers or devices like gameboy advance.
if you decide to make a internal controller, you can also build a switch.
this switch can disable or toggle different controller numbers like P1,P2,P3 or P4.
all you need to do is wire a controller to the mobo using my diagram, then, you will need to "cut" the "bidirectional data line" wire, then, put some wires from the mobo's P1 ,P2 ,P3 and P4's bidirectional data line to a switch.
it should looks like this pic.
(this switch does not have any internal bridges, except the brown moving thing wich bridge just 2 pins (upper and lower))
the resulting functions will be:
if moving the switch to the full left is position 1, and moving the switch to full right is position 5 it will be:
position 1 - internal controller disabled
position 2 - internal controller in player 1 mode
position 3 - internal controller in player 2 mode
position 4 - internal controller in player 3 mode
position 5 - internal controller in player 4 mode
I didnt tested this by myself yet, but I think it should works