For the 4x20 LCD display you can use the one from the 'Reichelt shop cart' or any other HD44780 compatible display ( LCD display on Aliexpress )

documentation

The WillFA7 diag board connected to the diag connector on the WillFA7 do provide display output and a subset of the game switches in order to be able to test WillFA7 'on the desk'.

WillFA7 diag controls:

5pin ICSP connector: to be able to program the PIC

contrast poti: for adjusting contrast of the LCD display

option switch: adjust (toggle) the display output: SYS3, SYS7, ..

game controls:

up-down/advance: to navigate in the Williams diagnostic menue

mem. prot: memory protection switch in coin door

Sol. Trig: Trigger for special solenoid #1

slam: slam switch

HS res. : High Score reset

Coins left/center/right: to be able to 'insert' coins

credit: credit button