Sometimes I get bored in video games and do strange things. This thrad is an open dumping ground for possibly interesting developments that result.
Zelda II: The Adventure of Link is the black sheep in the Zelda series for a number of reasons; among them are that it was the only game in the main series to be primarily side-scrolling, and it was also the only game in the series to use a life system. The latter of these is the basis for something the game developers didn't test entirely well, because the slow nature of levelling up means that they probably didn't expect anyone ever to get more than ten lives. However, the existence of emulators and turbo modes, plus an infinite one-up trick the game developers probably didn't intend (read the description of this video if you're unaware of it), means that it is now trivially to reach the game's life cap of 126. (Why 126 rather than 127 or 255 is beyond me, but anyway. Also, it's worth noting that unlike with Super Mario Bros., where the life counter just rolls back to 0 if you break it, here getting a new life just keeps you at 126).
As might be expected, the game's life counter starts behaving strangely after a certain point. From 11 to 36 it displays letters of the alphabet, as might perhaps be expected, and then from 37 to 48 it displays other symbols. After 48 is where it really starts to get weird, though. The symbol the game displays depends on your location, and it really isn't so much a symbol as it is... well, look.
Western Hyrule, Overworld
http://fools-gold.org/aaron/z2wos.png
Eastern Hyrule, Overworld
http://fools-gold.org/aaron/z2eos.png
Palace
http://fools-gold.org/aaron/z2ps.png
Great Palace
http://fools-gold.org/aaron/z2gps.png
(Disclaimer: These may not be the only sets of symbols displayed. For starters, I've also only tested the 126-life counter; I haven't tested any other values. Since certain numbers of lives display the same values at different parts of the game which usually have different symbols, it's possible there are additional differences at other parts of the game; presumably the symbols in common occur because the game loads those sprites into memory for both environments. Additionally, I haven't tested this everywhere on the world map, or in any palaces other than 5th one; it's possible the rest of Western Hyrule is different from Death Mountain, for example, from which I've taken these screenshots, and for reasons that may become apparent later, it's quite likely that different palaces load different symbols).
Looks like gibberish, doesn't it? But if we rearrange the symbols a bit, we get:
Western Hyrule, Overworld
http://fools-gold.org/aaron/z2wosrl.png
Eastern Hyrule, Overworld
http://fools-gold.org/aaron/z2eosrl.png
Palace
http://fools-gold.org/aaron/z2psrl.png
Great Palace
http://fools-gold.org/aaron/z2gpsrl.png
And I'm sure anyone who's played the game will recognise some of this, even though it's in different colours from what you're usually used to seeing.
What seems to be happening here is that the game is reading its own sprite data for the life counter. Most likely the data is stored in the same place as the text data; sprites and text are both displayed the same way by the Nintendo. Some of these parts of the data are clearly recognisable as enemy or environment sprites, but one noteworthy thing about it is that the game clearly isn't doubling up data for parts of the sprites that don't need it. So for instance while it's clear the Daira's legs are animated (in the Eastern Overworld symbols), its facial expression doesn't change, so that part of the sprite doesn't change (apart from the two variants necessary for different shield positions). The reason the programmers did this, of course, is that space on an 8-bit cartridge was at a premium, so the less data they had to duplicate, the better.
The other thing worth noting is that, as this might indicate, every single sprite and background you see in the game is constructed entirely from four colours (which is why the merchant and Zelda's tunics change colour alongside Link's in the first game). Different sprites and different backgrounds use different sets of four colours, to be sure, but regardless, they barely had anything to work with when constructing these environments. It's impressive that these games often look as detailed as they do.
More coming when I feel like it and/or discover it.
