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alphamecha-mkii

Gradius Box Art

s-h-o-w-a

A street in Tokyo, ca. 1970

demoncity

WHISPER OF THE HEART (1995) dir. Yoshifumi Kondō

commodorez

Debugging of the Cactus Video Card Mk II Rev B continues.

The last issue remaining with this design is fixing the inconsistent reset of the video state machine. About 10-20% of the time now, either on power on (though more likely from pressing the reset switch), the state machine will end up in a bad state and output incorrect video, requiring another reset before it settles in the expected pattern.

Initially, I thought the problem was purely from the very slow rise time of the /RESET line (the dark blue trace at the bottom), but that only seems to be part of the problem. I'm using a spare AND gate to smooth the signal out as seen on the /VRES line (the yellow trace at the top of the scope). What I really need is a Schmitt trigger circuit that I can't really justify the space for on the PCB. I'm also not sure if the settling noise seen on the scope is an instrumentation problem, or the result of my temporary wiring job for testing.