Handling Writing to ROM or out of range addresses

Discuss emulation of the Nintendo Entertainment System and Famicom.

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thefox
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Re: Handling Writing to ROM or out of range addresses

Post by thefox »

rainwarrior wrote:
ace314159 wrote:What I don't understand is the diference between a power cycle and reset. I couldn't find an explanation on the page or through a Google search. Is a reset just a way to change the ROM without resetting all of the registers, and on a physical device without turning it on and off?
The NES and famicom have two separate buttons: POWER and RESET.

The power switch removes power from the system and turns it off. The reset button doesn't turn anything off, it just restarts the software from the beginning.
There's a minor additional difference in Famicom vs NES in regard to reset behavior: On NES reset affects both CPU and PPU (CPU is reinitialized, starting the restarting the software; PPU is reinitialized), on Famicom reset only affects the CPU. So, on Famicom, for example, if PPU rendering was enabled before reset was pushed, it will stay enabled after reset is released. (However, most games will disable rendering as one of the very first things they do. This is the reason why most games start with something like LDA #0 / STA $2000 / STA $2001.) All in all, it doesn't matter much for emulation, unless you strive to emulate every configuration perfectly.
Download STREEMERZ for NES from fauxgame.com! — Some other stuff I've done: fo.aspekt.fi
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