Logic levels question 6502A (Missile command)

I am trying to trouble shoot a board. I am getting some odd responses
reading the roms. I noticed that the address lines coming from the 6502
seem to be going high at 3.5 - 3.7 vdc. I suspect this is causing some of
the ttl to not latch high.

This is checked through a meter using the fluke to read a particular address
on a loop and using my scope for the same and while running the game.

Is this a normal value? I don't see any pull-ups on the address lines on
the schematic.

David

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Received on Sat Nov 5 14:33:35 2011