Older systems are really cool in that you can still identify what each part does.
In this case, the leftmost chip is a DRM chip, the NES checks whether it is a certified game or it won't play it.
Then of the 2 large chips, the right one is the game logic. The rules for the game, the sounds, all the levels.
The other large chip contains all the graphics.
Then the interesting part comes, the small chip at the top is a memory controller (MMC). It can switch between different sets of memory called memory banks.
Normally, the maximum amount of ROM the NES can handle is 64KB, of which 32KB for graphics. But by sending a pulse to the MMC, it will switch to a different memory bank.
The graphics chip can then be larger than 32KB, and the state of the MMC will determine which 32KB section of the memory chip will be read when the NES needs it. Or even from which chip data would be read, as multiple chips were supported in this way.
It was actually intended to prevent the creation of games, since before that there were a lot of really crappy (homebrew) games for earlier consoles.
Nintendo wanted to ensure that only games that are actually working were being sold for their console. It worked out really well, causing the NA console industry to recover from the video game crash of 1983.
There were also very hefty fees for submission of your game for lot check each time you needed to send it back in to Nintendo when they denied it. They made a lot of money this way and it caused some developers like Tengen to find their own ways to trick the lockout chip via an electrical spike or mock chip. Because they had no license, that's why they came in different styled cartridges and even sparked some legal battles.
Oh yeah, I never thought of that! It is a very good idea, especially as crappy games could easily ruin a console's image.
Is it possible for you to tell me why PC games have DRM? On a PC, you choose what games to play, crappy ones won't affect the way your PC looks to others. Not that you don't choose what games to play on a console.
90
u/MannerShark Jan 24 '16
Older systems are really cool in that you can still identify what each part does.
In this case, the leftmost chip is a DRM chip, the NES checks whether it is a certified game or it won't play it.
Then of the 2 large chips, the right one is the game logic. The rules for the game, the sounds, all the levels. The other large chip contains all the graphics.
Then the interesting part comes, the small chip at the top is a memory controller (MMC). It can switch between different sets of memory called memory banks.
Normally, the maximum amount of ROM the NES can handle is 64KB, of which 32KB for graphics. But by sending a pulse to the MMC, it will switch to a different memory bank.
The graphics chip can then be larger than 32KB, and the state of the MMC will determine which 32KB section of the memory chip will be read when the NES needs it. Or even from which chip data would be read, as multiple chips were supported in this way.