Found these inside a non-working 71B

[Paul Berger (Canada)]

(03-11-2018 09:51 PM)MikeSD Wrote:  

Its hard to say why it is this way, perhaps when they where originally planning the 71B they thought they might need a 6th module inside and laid out the board to accommodate that, but later changed their minds and instead of removing all the pads just joined the the two pads so that if in the future the did need the top left it would be a simple cut rather than having to layout and produce a new board. I have run into odd little things like this before and I try not to get too wound up with why, I am just happy that they work. They may have used pin 10 because it was easier to route the connections and 10, 11 and 12 are all not connected on RAM / ROM modules. The connection from Dout of U8 actually goes though pin 11 of top left, pin 11 of top left and bottom left are joined and 11 of bottom left goes to pin 8 on the top side of the board under the module I am sure this was done for ease of routing the signal lines.