no nothing this is not the first time i've seen this the crtc is not generating horizontal sync the gate array stops generating interrupts and everything locks up so let's look in detail about what those signals do and how they depend on each other the zNUMBER_TOKEN receives interrupt signals from the gate array periodically and uses them to scan the keyboard and do other tasks specifically it should get interrupts regularly every NUMBER_TOKEN milliseconds this can also be used by the code to time things relative to the display of the image in order to generate those interrupts the gate array uses the horizontal sync signal every time it receives one it increments a counter and whenever the counter reaches NUMBER_TOKEN it triggers the interrupt so the lack of horizontal sync in the crt controller is propagating all the way to the cpu and causing no interrupts it's possible that the problem may be coming from the gate array since that's also in charge of generating the images if there's something wrong with it it could cause that lock up in the cycle of interrupts and signals and whatnot so let's just swap it out for a working gate array okay let's check the sync signals with the new gate array so it should be vsync in NUMBER_TOKEN and now that looks just as slow and horizontal sank nothing okay so i guess that wasn't it so i think given everything we've seen it's time for a desoldering montage
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