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Comment by upupandup | Hacker News Reader

Even more curious is how do ppl discover the hex codes for like Gameshark? I had a friend who would just guesstimate and successfully able to manipulate playstation games. It was fascinating to watch.

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I'm not sure if this applies to the playstation, but I remember the nintendo 64 gameshark I had had some "code finding" features that involved using a button on the cartridge to filter down to memory addresses that had changed a certain way since the last button press. This meant that if you were looking for say, the address where your character's health was stored, you could press the button, get hit in the game, press the button again, and search for values in memory that had decreased since the last button press. Doing this several times was a fairly reliable way of finding things. I'm a bit fuzzy on the details but that was the general idea.

Most modern emulators have similar but much more fleshed out features. They're nice not only for finding cheat codes but for reverse engineering games for the purposes of making romhacks or tool assisted speedruns and things like that.

huh, okay I always wondered what the button did. I always assumed it was to 'activate' codes that were input, maybe for a different game that I hadnt played yet and thus hadn't needed to use it yet.

I think you could also configure some codes to work that way- like "set the value at this memory address to 0 when you press the button".

For some reason I thought I had remembered reading about pressing the button for extra lives, or for clipping, but not having the game it was for, when I was reading about it at the time.

Incidentally, Game genie and Gameshark were the first time I realized I was committing piracy (or any crime), when I was asked to leave a store for writing down a code that was in one of those 10,000 Game Codes books. It's been a long sordid tale of hidden algebra notecards and microscopic formula sheets ever since.

This life of crime chose me.

At a basic level, this is how modern tools like CheatEngine work today. Find all the memory addresses containing your current health level. Do something to manipulate that value, find all the addresses that reflect the new value, rinse and repeat until you know where your health is stored, then write whatever you want to that address.

It can do more than that of course, but it's cool to see that the gameshark I had as a little kid worked in a similar fashion.

My main exposure to this technique was with the various in-game plugins one could install on a hacked Sony PSP.

Even though I had an interest in programming from a young age, before learning how to use those plug-ins, it hadn't really dawned on me that everything in the game, like your health, location, stats, and even your characters current action, were all states stored in memory somehow.

Using those plugins (or similar), you can narrow down and manipulate all sorts of values. Infinite ammo? Just lock the value to something greater than 0. Even just locking the height value of your position opened up interesting avenues because you could circumvent gravity in a way that was relatively easy to find.

Tangentially, if this sort of thing entertains you as it does me, the magic system in the Magic 2.0 book series by Scott Meyer effectively works like a cheat engine.

This is actually amazing:

> The code is GOSSIP (amazing coincidence that it happens to also be an English word). This works in Capcom's Ghosts 'n Goblins to start your player with a really funky weapon.

Oh, the potential for easter eggs if you anticipated the use of a Game Genie by players, this was meta-gaming at its earliest in strictly offline mode. You could even hide codes in-story for later replays and whatnot. What's not to love about such a hacky mode of expression, a hacking-friendly barebones paradigm.

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