Why did you have to hold the reset button before powering off

RAM mechanics I suppose.

>>3604248
It prevented a potential short circuit, I think, which would wipe your battery save

It help prevent voltage spikes to the cartage that could wipe the battery backup memory.

The NES originally was never designed to be electronically safe for battery backups, it was something added to game carts a few years later.

>>3604248
It basically put the console into a state where it was guaranteed to not be writing data to the cartridge, preventing the slim but very real chance that bad data could be written to the save, doing funny shit or rendering it unloadable.

Saving data to the NES was pretty much a weird hack. Someone can probably give a more technical answer.

The NES was released with a design flaw that caused random data to be written to random locations when the power was turned off. This wasn't considered a problem originally because no games in 1985/86 had battery saves. But when Zelda introduced save data, it became a problem because there was a chance the system could randomly overwrite parts of the save file.

By pure luck it turned out holding the reset button prevented the random writes, so they encouraged you to hold it while turning off the system to prevent the possibility of data corruption.

I have no idea if the design flaw was fixed in later NES models. I tested it on my own system by turning the system off without holding reset about 10 times in a row, but the data never got deleted.

>>3604248
I remember Nintendo Power talking about this in one of the early issues.