Ok thanks Neal have a great vacation and don't think about IORQs and the like anymore
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In terms of bending the pin, no need as removing IC31 from its socket etc. effectively does the same thing. However.....
I have just noticed that /NMI on the CPU is permanently held low presumably by IC 19 pin 15 (LK4 is connected A-B). My understanding is that /NMI is used to indicate the blanking period. With /NMI low would that not prevent IORQ from doing its thing, leaving me with a blank screen into the bargain.