That's odd. Haven't experienced that before.

Are you sure that the DOS application isn't writing the file only when the application exits?

CTRL-F4 is used to force DOSBox to re-read the current directory structure, but I don't think that has anything to do with writing to disk.

DOSBox, like most C programs, uses write buffering (see here) for better performance. The data is written to disk when the buffer becomes full, so I guess the application is only writing a small amount and then leaving the file open. Closing a file will, of course, write all data to disk; and because it's your application you may be able to add more frequent closing.

Some time ago I made a TSR program (see here) to run inside DOSBox that has the effect of flushing writes to disk immediately. It was intended as a workaround for a particular issue with a game that has since been resolved, but it may be effective for your purpose. However, do note that it mostly negates the performance benefits of the buffering.

True. How do you determine that the file is not there? Through the app in Dosbox (then the ctrl-f4 is important) or through. File manager in your host.

ripsaw8080 wrote:

DOSBox, like most C programs, uses write buffering (see here) for better performance. The data is written to disk when the buffer becomes full, so I guess the application is only writing a small amount and then leaving the file open. Closing a file will, of course, write all data to disk; and because it's your application you may be able to add more frequent closing.
Some time ago I made a TSR program (see here) to run inside DOSBox that has the effect of flushing writes to disk immediately. It was intended as a workaround for a particular issue with a game that has since been resolved, but it may be effective for your purpose. However, do note that it mostly negates the performance benefits of the buffering.

Unfortunately it is not my application, its a 3rd party DOS exe which does some data crunching to generate a bin file 😐 and since its a legacy application (1998 to be precise) I do not have the source code of the same to add the fflush

Dominus wrote:

True. How do you determine that the file is not there? Through the app in Dosbox (then the ctrl-f4 is important) or through. File manager in your host.

Jorpho wrote:

Are you sure that the DOS application isn't writing the file only when the application exits?

So this is how I checked:

• 1. I started DOSBox and launched my application
  2. Application creates a file test.bin
  3. The size of test.bin is 0 (The usual behaviour on my windows machine is the size of test.bin increases)
  4. I quit the DOSBox window and test.bin is now showing 1024 Bytes as the size

I'm wondering if its got anything to do with the my Ubuntu system settings, will read that up a little to see if there is anything on the system that I need to tweak to ensure the file gets written to immediately. If you guys have any other ideas, please let me know! cheers!