SEUD only has keyboard control. To use interface 2 joystick you have to poke the addresses in your menu. In my games I use interface 2 port 2 which is the same as keys 6,7,8,9,0
This is what I have currently in my code for Joystick Sinclair (the numbers are decimal values) probably it is not correct... I thought it was Sinclair 1... I will use your values , thanks very very much!!
ld a,3
ld (50501),a
ld a,11
ld (50502),a
ld a,4
ld (50503),a
ld a,19
ld (50504),a
ld a,35
ld (50505),a