I have a "shift" question too...
What happens if I hardwire the "shift button" input and one other "button" input together on one single button? Will it trigger the shifted function of that key? This way I could use more functions without pressing two buttons at once. You know what I mean?
Sounds like you want to have a dedicated button for a shifted function like the green "P1 Coin" button below.
To convert the diagram for IPac, the "Shift (D7)" input port is "P1 Start".
With no buttons pushed, the input ports are all at a logic high. (5v)
When you press the green button:
- Ground is applied to the cathode (band end) of the two lower diodes
- Both diodes are forward biased
- They conduct and apply ground to both the Shift port and P1B2 port ==> P1B2 shifted function
When you press the blue button:
- Ground is applied to the anode (non-band end) of the bottom diode
- The diode is not forward biased so it does not conduct ==> blocks the ground from reaching the cathode (band end) of the other diode
- Ground is also applied to P1B2 port ==> P1B2 normal function
If you only need one dedicated button, you can use the "backwards wiring" trick mentioned
here for controlling MagnaSave/Upper Flipper with one pinball button.
(more than one dedicated button for shifted functions requires using diodes like below)
Scott