Front Panel Daughterboard

The Front Panel Daughterboard is located in region A2 of the jwdonal schematic

The Front Panel Daughterboard (known as the "Front Connector Unit in the official Nintendo documentation^[1] ) is situated perpendicular to the SNES Motherboard. It contains the two controller ports and the red power indicator LED. In the jwdonal schematic, pins 4, 6, 5, and 7 are named after JOYA and JOYB, the fullsnes common names for the read-only joypad input registers A & B, who's addresses are 4016h and 4017h.

References

1. Figure 2-22-1, "Super NES Functional Block Diagram" on page 2-22-2 of Book I of the official Super Nintendo development manual
2. http://problemkaputt.de/fullsnes.htm#snescontrollersioportsmanualreading