Setting an Entry Breakpoint in DOSBox Debugger

When working with 32-bit code, it can be challenging to set breakpoints and debug your application effectively. In this article, we'll explore how to set entry breakpoints in DOSBox debugger for 32-bit code.

DOSBox is a popular emulator that allows you to run old MS-DOS games and applications on modern operating systems. Its debugger provides a range of features to help developers test and debug their code. However, setting breakpoints for 32-bit code can be tricky.

In the case of DOS4GW bound EXE files, these files consist of two parts: a 16-bit DOS stub that executes dos4gw.exe, and a 32-bit LE (Linear Executable) that is loaded by the dos4gw.exe loader. To explore the internal workings of these files, it's essential to be able to set breakpoints on the 32-bit code.

Unfortunately, setting breakpoints on 32-bit code in DOSBox debugger can be challenging. In our experience, the debugger does not provide a straightforward way to place breakpoints on 32-bit code. However, there are some workarounds that can help you achieve your goal.

One approach is to use the `INT` command (7.03-28) to cause software interrupts in your program. This allows you to set breakpoints in your code and step through it line by line. Another option is to use hardware devices to send interrupt requests via the IRQ lines (IRQ 00 – IRQ 15). These interrupts can be used to trigger your desired action.

In addition, it's possible to invoke exceptions within the CPU itself. This can be done using the `F10` key in DOSBox debugger, which allows you to step through your code and set breakpoints as needed.

To illustrate this process, let's consider an example. Suppose we have a 32-bit code that we want to debug using DOSBox debugger. We can use the `INT` command to cause software interrupts in our program, allowing us to set breakpoints and step through our code line by line.

In conclusion, setting entry breakpoints in DOSBox debugger for 32-bit code requires some creativity and experimentation. By using software interrupts, hardware devices, or CPU exceptions, you can set breakpoints and debug your 32-bit code effectively. With practice and patience, you'll be able to master the art of debugging 32-bit code in DOSBox debugger.

Dosbox debugger set entry breakpoint