Pokemon Crystal - "Slowing down" the CPU

Channel:

Crystal_

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12,600

Published on February 17, 2015 6:19:23 PM ● Video Link: https://www.youtube.com/watch?v=5QGYjcdqqFE

Game:

Pokémon Crystal (2000)

Duration: 4:22

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188

We can modify the values in the Timer Modulo (FF06) and Timer Control (FF07) registers to make the CPU have to attend the timer interrupt so frecuently that it has very little time to perform other tasks. This way we can do some cool things, such as watching the attack animations in "slow motion".

It would be possible to do this in a real Gameboy by writing to these two hram addresses through the coin case glitch (arbitrary code execution) in Pokemon Gold/Silver. However only Pokemon Crystal uses the timer interrupt at all, so in Pokemon G/S you'd have to enable it by setting bit 2 of the Interrupt Enable Register (FFFF). In addition, since the Timer Interrupt vector is defined as a single reti instruction, it makes it more difficult to get the desired result due to the timing (but would still be possible).

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