Main Board 50XXX series
Connection on the main bord - top row near the yellow 'TOP1' label. Shared by all 50XXX boards.
Wiring / pinout main CPU board
.
| TOP 1 | SCK of CPU display board |
| TOP 2 | MISO of CPU display board |
| TOP 3 | MOSI of CPU display board |
| TOP 10 | RST of CPU display board |
| TOP 13,14 | TX/RX of CPU display board |
| BOT far left/right | Power |
Progamming cable ATMEL 
to which this needs to be connected.
