/vr/ - Retro Games

Introducing the FCEUX Debugger

See animated image for a rundown of the Debugger window.

The Debugger allows you to examine the state of the NES at any given time and view the code as it is executing. 6502 Assembly and the NES architecture in general is beyond the scope of this post, but resources are available online that describe these topics in detail.

When a game is running, if you just pause the emulation as it speeds through frame after frame, there is no telling where it will stop, so we use breakpoints to stop the program where we want it to. The breakpoints are a trap you set on a certain address (or range of addresses) that will pause the program when it tries to do something to that address, such as read from, write to, or execute and instruction on that address (or any combination thereof.) Conditions can also be specified ie: only break when you write 0x05 or higher to this address.

Once the breakpoint has triggered, the code the will display in the left window. To the right you will find all the different sections of the processor, such as what the current stack looks like, the contents of the registers and so on. By clicking the buttons near the top of that section, you can step through the code and watch it execute. "Run" simply continues running the program as normal. "Step Into" executes only one line of code and will follow into any subroutines that may get called. "Step Over" executes the next line of code but will do a subroutine before breaking again on the line after it returns. "Step Out" runs until the next RTS command, useful for getting out of a function and getting to the code that called it. "Run Line" will execute as much code as would be done in the time it takes to complete one scanline. "128 Lines" does the same but for about half a screen worth of scanlines.

Bookmarks can help you identify locations in the code.

Hint: Double clicking a breakpoint will toggle it on and off, and hex editor will highlight recently changed values.

>Introducing the FCEUX Debugger

See animated image for a rundown of the Debugger window.

The Debugger allows you to examine the state of the NES at any given time and view the code as it is executing. 6502 Assembly and the NES architecture in general is beyond the scope of this post, but resources are available online that describe these topics in detail.

When a game is running, if you just pause the emulation as it speeds through frame after frame, there is no telling where it will stop, so we use breakpoints to stop the program where we want it to. The breakpoints are a trap you set on a certain address (or range of addresses) that will pause the program when it tries to do something to that address, such as read from, write to, or execute and instruction on that address (or any combination thereof.) Conditions can also be specified ie: only break when you write 0x05 or higher to this address.

Once the breakpoint has triggered, the code the will display in the left window. To the right you will find all the different sections of the processor, such as what the current stack looks like, the contents of the registers and so on. By clicking the buttons near the top of that section, you can step through the code and watch it execute. "Run" simply continues running the program as normal. "Step Into" executes only one line of code and will follow into any subroutines that may get called. "Step Over" executes the next line of code but will do a subroutine before breaking again on the line after it returns. "Step Out" runs until the next RTS command, useful for getting out of a function and getting to the code that called it. "Run Line" will execute as much code as would be done in the time it takes to complete one scanline. "128 Lines" does the same but for about half a screen worth of scanlines.

Bookmarks can help you identify locations in the code.

Hint: Double clicking a breakpoint will toggle it on and off, and hex editor will highlight recently changed values.

>Introducing the FCEUX Debugger

See animated image for a rundown of the Debugger window.

The Debugger allows you to examine the state of the NES at any given time and view the code as it is executing. 6502 Assembly and the NES architecture in general is beyond the scope of this post, but resources are available online that describe these topics in detail.

When a game is running, if you just pause the emulation as it speeds through frame after frame, there is no telling where it will stop, so we use breakpoints to stop the program where we want it to. The breakpoints are a trap you set on a certain address (or range of addresses) that will pause the program when it tries to do something to that address, such as read from, write to, or execute and instruction on that address (or any combination thereof.) Conditions can also be specified ie: only break when you write 0x05 or higher to this address.

Once the breakpoint has triggered, the code the will display in the left window. To the right you will find all the different sections of the processor, such as what the current stack looks like, the contents of the registers and so on. By clicking the buttons near the top of that section, you can step through the code and watch it execute. "Run" simply continues running the program as normal. "Step Into" executes only one line of code and will follow into any subroutines that may get called. "Step Over" executes the next line of code but will do a subroutine before breaking again on the line after it returns. "Step Out" runs until the next RTS command, useful for getting out of a function and getting to the code that called it. "Run Line" will execute as much code as would be done in the time it takes to complete one scanline. "128 Lines" does the same but for about half a screen worth of scanlines.

Bookmarks can help you identify locations in the code.

Hint: Double clicking a breakpoint will toggle it on and off, and hex editor will highlight recently changed values.

>Introducing the FCEUX Debugger

See animated image for a rundown of the Debugger window.

The Debugger allows you to examine the state of the NES at any given time and view the code as it is executing. 6502 Assembly and the NES architecture in general is beyond the scope of this post, but resources are available online that describe these topics in detail.

When a game is running, if you just pause the emulation as it speeds through frame after frame, there is no telling where it will stop, so we use breakpoints to stop the program where we want it to. The breakpoints are a trap you set on a certain address (or range of addresses) that will pause the program when it tries to do something to that address, such as read from, write to, or execute and instruction on that address (or any combination thereof.) Conditions can also be specified ie: only break when you write 0x05 or higher to this address.

Once the breakpoint has triggered, the code the will display in the left window. To the right you will find all the different sections of the processor, such as what the current stack looks like, the contents of the registers and so on. By clicking the buttons near the top of that section, you can step through the code and watch it execute. "Run" simply continues running the program as normal. "Step Into" executes only one line of code and will follow into any subroutines that may get called. "Step Over" executes the next line of code but will do a subroutine before breaking again on the line after it returns. "Step Out" runs until the next RTS command, useful for getting out of a function and getting to the code that called it. "Run Line" will execute as much code as would be done in the time it takes to complete one scanline. "128 Lines" does the same but for about half a screen worth of scanlines.

Bookmarks can help you identify locations in the code.

Hint: Double clicking a breakpoint will toggle it on and off, and hex editor will highlight recently changed values.

>Introducing the FCEUX Debugger

See animated image for a rundown of the Debugger window.

The Debugger allows you to examine the state of the NES at any given time and view the code as it is executing. 6502 Assembly and the NES architecture in general is beyond the scope of this post, but resources are available online that describe these topics in detail.

When a game is running, if you just pause the emulation as it speeds through frame after frame, there is no telling where it will stop, so we use breakpoints to stop the program where we want it to. The breakpoints are a trap you set on a certain address (or range of addresses) that will pause the program when it tries to do something to that address, such as read from, write to, or execute and instruction on that address (or any combination thereof.) Conditions can also be specified ie: only break when you write 0x05 or higher to this address.

Once the breakpoint has triggered, the code the will display in the left window. To the right you will find all the different sections of the processor, such as what the current stack looks like, the contents of the registers and so on. By clicking the buttons near the top of that section, you can step through the code and watch it execute. "Run" simply continues running the program as normal. "Step Into" executes only one line of code and will follow into any subroutines that may get called. "Step Over" executes the next line of code but will do a subroutine before breaking again on the line after it returns. "Step Out" runs until the next RTS command, useful for getting out of a function and getting to the code that called it. "Run Line" will execute as much code as would be done in the time it takes to complete one scanline. "128 Lines" does the same but for about half a screen worth of scanlines.

Bookmarks can help you identify locations in the code.

Hint: Double clicking a breakpoint will toggle it on and off, and hex editor will highlight recently changed values.

>Introducing the FCEUX Debugger

See animated image for a rundown of the Debugger window.

The Debugger allows you to examine the state of the NES at any given time and view the code as it is executing. 6502 Assembly and the NES architecture in general is beyond the scope of this post, but resources are available online that describe these topics in detail.

When a game is running, if you just pause the emulation as it speeds through frame after frame, there is no telling where it will stop, so we use breakpoints to stop the program where we want it to. The breakpoints are a trap you set on a certain address (or range of addresses) that will pause the program when it tries to do something to that address, such as read from, write to, or execute and instruction on that address (or any combination thereof.) Conditions can also be specified ie: only break when you write 0x05 or higher to this address.

Once the breakpoint has triggered, the code the will display in the left window. To the right you will find all the different sections of the processor, such as what the current stack looks like, the contents of the registers and so on. By clicking the buttons near the top of that section, you can step through the code and watch it execute. "Run" simply continues running the program as normal. "Step Into" executes only one line of code and will follow into any subroutines that may get called. "Step Over" executes the next line of code but will do a subroutine before breaking again on the line after it returns. "Step Out" runs until the next RTS command, useful for getting out of a function and getting to the code that called it. "Run Line" will execute as much code as would be done in the time it takes to complete one scanline. "128 Lines" does the same but for about half a screen worth of scanlines.

Bookmarks can help you identify locations in the code.

Hint: Double clicking a breakpoint will toggle it on and off, and hex editor will highlight recently changed values.