3.1 ROM problem - strange 3.0 ROM wiring

[vic20owner]

Uhoh! If I remember correctly, you align the roms with the RIGHT side of the socket, not the left side.  So, pin 1 of the chip actually goes into the pin 2 hole.

Is that how you installed them?

If so, then it could actually be that you have a motherboard which had a production bug which was "fixed" at the factory with those additional sockets.  You may need to swap those addresses after all.

The fact that BOTH roms required the switch makes me think it's the motherboard not the roms.

[vic20owner]

lurkist, what rev motherboard was that you saw the same rom mod on?

This may be a clue.  Also, were they 3.0 roms, and did they have the same chip numbers?

This could be the answer we are looking for.