/vr/ - Retro Games

>Introducing the Code Data Logger

The Code Data Logger is a simple but useful tool. It is helpful in developing a proper disassembly.

See, the only thing a computer can deal in is binary, ones and zeros. That's it. What those bits mean is determined by how it is interpreted. Is it a number, or a letter? Maybe it's an instruction or a pointer to somewhere else in memory. You can't actually know what some chunk of bits in memory are based only on the bits themselves. However the computer doesn't care. You just give it a starting point and it goes off on it's own. It will take the first byte and assume it is an instruction, then load the next zero or more bytes (however much as that particular command needs) as an operand, executes it, then does the very next byte.

So to disassemble machine code back into code, you could start at the beginning and sort of unzip your way through the file, except for the fact that you can change which byte is the next byte to execute via jumps, branches, straight up stack manipulation, or maybe even witchcraft (self modifying code.) These factors make such an approach...

complicated.

Doing a complete job would end up requiring you to emulate the entire system. But hey! You're doing that anyways when you play a ROM on the emulator! This is where the Code Data Logger comes in. You start the logger and it will keep track of every byte in the entire file and watches as the instructions are executed. It will mark each byte as having been used as Code (instructions to the processor) or Data (used by the processor to do the command). You can then play the game until you've done everything the game can do, and by then you'll have marked up the entire file. A disassembler can then use this file to help it create accurate source code which, should, recompile into back into the same game you started with.

Now if you don't understand why anyone would get excited to have the source code for a game, don't worry, this tool just isn't for you.

>Introducing the Code Data Logger

The Code Data Logger is a simple but useful tool. It is helpful in developing a proper disassembly.

See, the only thing a computer can deal in is binary, ones and zeros. That's it. What those bits mean is determined by how it is interpreted. Is it a number, or a letter? Maybe it's an instruction or a pointer to somewhere else in memory. You can't actually know what some chunk of bits in memory are based only on the bits themselves. However the computer doesn't care. You just give it a starting point and it goes off on it's own. It will take the first byte and assume it is an instruction, then load the next zero or more bytes (however much as that particular command needs) as an operand, executes it, then does the very next byte.

So to disassemble machine code back into code, you could start at the beginning and sort of unzip your way through the file, except for the fact that you can change which byte is the next byte to execute via jumps, branches, straight up stack manipulation, or maybe even witchcraft (self modifying code.) These factors make such an approach...

complicated.

Doing a complete job would end up requiring you to emulate the entire system. But hey! You're doing that anyways when you play a ROM on the emulator! This is where the Code Data Logger comes in. You start the logger and it will keep track of every byte in the entire file and watches as the instructions are executed. It will mark each byte as having been used as Code (instructions to the processor) or Data (used by the processor to do the command). You can then play the game until you've done everything the game can do, and by then you'll have marked up the entire file. A disassembler can then use this file to help it create accurate source code which, should, recompile into back into the same game you started with.

Now if you don't understand why anyone would get excited to have the source code for a game, don't worry, this tool just isn't for you.

>Introducing the Code Data Logger

The Code Data Logger is a simple but useful tool. It is helpful in developing a proper disassembly.

See, the only thing a computer can deal in is binary, ones and zeros. That's it. What those bits mean is determined by how it is interpreted. Is it a number, or a letter? Maybe it's an instruction or a pointer to somewhere else in memory. You can't actually know what some chunk of bits in memory are based only on the bits themselves. However the computer doesn't care. You just give it a starting point and it goes off on it's own. It will take the first byte and assume it is an instruction, then load the next zero or more bytes (however much as that particular command needs) as an operand, executes it, then does the very next byte.

So to disassemble machine code back into code, you could start at the beginning and sort of unzip your way through the file, except for the fact that you can change which byte is the next byte to execute via jumps, branches, straight up stack manipulation, or maybe even witchcraft (self modifying code.) These factors make such an approach...

complicated.

Doing a complete job would end up requiring you to emulate the entire system. But hey! You're doing that anyways when you play a ROM on the emulator! This is where the Code Data Logger comes in. You start the logger and it will keep track of every byte in the entire file and watches as the instructions are executed. It will mark each byte as having been used as Code (instructions to the processor) or Data (used by the processor to do the command). You can then play the game until you've done everything the game can do, and by then you'll have marked up the entire file. A disassembler can then use this file to help it create accurate source code which, should, recompile into back into the same game you started with.

Now if you don't understand why anyone would get excited to have the source code for a game, don't worry, this tool just isn't for you.

>Introducing the Code Data Logger

The Code Data Logger is a simple but useful tool. It is helpful in developing a proper disassembly.

See, the only thing a computer can deal in is binary, ones and zeros. That's it. What those bits mean is determined by how it is interpreted. Is it a number, or a letter? Maybe it's an instruction or a pointer to somewhere else in memory. You can't actually know what some chunk of bits in memory are based only on the bits themselves. However the computer doesn't care. You just give it a starting point and it goes off on it's own. It will take the first byte and assume it is an instruction, then load the next zero or more bytes (however much as that particular command needs) as an operand, executes it, then does the very next byte.

So to disassemble machine code back into code, you could start at the beginning and sort of unzip your way through the file, except for the fact that you can change which byte is the next byte to execute via jumps, branches, straight up stack manipulation, or maybe even witchcraft (self modifying code.) These factors make such an approach...

complicated.

Doing a complete job would end up requiring you to emulate the entire system. But hey! You're doing that anyways when you play a ROM on the emulator! This is where the Code Data Logger comes in. You start the logger and it will keep track of every byte in the entire file and watches as the instructions are executed. It will mark each byte as having been used as Code (instructions to the processor) or Data (used by the processor to do the command). You can then play the game until you've done everything the game can do, and by then you'll have marked up the entire file. A disassembler can then use this file to help it create accurate source code which, should, recompile into back into the same game you started with.

Now if you don't understand why anyone would get excited to have the source code for a game, don't worry, this tool just isn't for you.

>Introducing the Code Data Logger

The Code Data Logger is a simple but useful tool. It is helpful in developing a proper disassembly.

See, the only thing a computer can deal in is binary, ones and zeros. That's it. What those bits mean is determined by how it is interpreted. Is it a number, or a letter? Maybe it's an instruction or a pointer to somewhere else in memory. You can't actually know what some chunk of bits in memory are based only on the bits themselves. However the computer doesn't care. You just give it a starting point and it goes off on it's own. It will take the first byte and assume it is an instruction, then load the next zero or more bytes (however much as that particular command needs) as an operand, executes it, then does the very next byte.

So to disassemble machine code back into code, you could start at the beginning and sort of unzip your way through the file, except for the fact that you can change which byte is the next byte to execute via jumps, branches, straight up stack manipulation, or maybe even witchcraft (self modifying code.) These factors make such an approach...

complicated.

Doing a complete job would end up requiring you to emulate the entire system. But hey! You're doing that anyways when you play a ROM on the emulator! This is where the Code Data Logger comes in. You start the logger and it will keep track of every byte in the entire file and watches as the instructions are executed. It will mark each byte as having been used as Code (instructions to the processor) or Data (used by the processor to do the command). You can then play the game until you've done everything the game can do, and by then you'll have marked up the entire file. A disassembler can then use this file to help it create accurate source code which, should, recompile into back into the same game you started with.

Now if you don't understand why anyone would get excited to have the source code for a game, don't worry, this tool just isn't for you.