You can see in the (partial) schematics that these are used for the colours. This had an effect (normally it shouldn’t as working logic drive outputs can out-do the capacitance effects of your fingers), so I honed it down to a 74LS151. It seemed intermittent and gradual so I took the hack route of putting my hand over the pins on the back of the board. The graphics issue seemed to be at the colour mixer stage – after all layers are combined. It was clear that there were graphics problems and there was no sound (just blips and a lot of heat from the amplifier IC). It’s a good trick – gives you breathing time to see what might be playing up, should the game be capable of running in a faulty state – this board was. ![]() ![]() Unlikely all this went wrong suddenly one morning.Ī little bit of Googling showed there’s a simple link to make to bypass the watchdog (regards to Caius). ![]() Lots of things as it turned out, but initially it just sat in a constant reset within milliseconds of power-on.
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