"James" wrote in message
...

Haven't looked that the circuit, but if they follow normal convention.....

"A.Grnd" - From J4 (A4) - (Is that 'all ground'?)

Probably Analog ground - perhaps for joystick potentiometer or speaker.

"V.Batt" - From J4 (A5) - (Something battery?)

Battery Voltage.

"Logic Grnd" - From J4 (A2)(B3)(C3) and J5 (B4) - (Special Ground?)

Logic Ground - eg seperate to Analog ground so as not to put digital noise
on the analog signals via a common ground.

Normally Logic Ground and Analog ground are connected together at only one
point somewhere. That point is usually either in the power supply or
somewhere where digital and analog worlds meet eg near the input of any
analog to digital converter or preamp.