Port
From veswiki
The VES has four usable 8-bit data ports in the console, port 0 and 1 that are in the 3850 CPU and port 4 and 5 on one of the 3851 Program Storage Units. These I/O:s are hooked to specific functions as shown in the table below.
Port 0
0 TIME console button
1 MODE console button
2 HOLD console button
3 START console button
4 - not connected -
5 ARM (sound/graphics)
6 Enable in-signal from controllers
7 - not connected -
Port 1
0
1
2
3
4
5
6
7
Port 4
0
1
2
3
4
5
6
7
Port 5
0 Video Vertical A
1 Video Vertical B
2 Video Vertical C
3 Video Vertical D
4 Video Vertical E
5 Video Vertical F
6 Tone AN (beep sound)
7 Tone BN (beep sound)