First post, by Nicknine
I was originally contemplating making a separate topic for each game but I suspect that all of this might be connected. DOSBox modem emulation appears to unstable as I'm facing several problems in different games/apps.
1) Modem commands would sometimes arrive with garbage mixed in as seen in the console.
2) Duke Nukem 3D crashes on the calling DOSBox instance when starting a level in modem play with "INVALID GAME PACKET!!! (6 too many bytes)" error while DosBox console spams "illegal read" errors. Curiously, this does not happen if two DOSBox instances are linked together with a comms program like Telemate and "Already connected" is selected in Setup program.
3) Doom has the reverse issue. Making the call using Setup appears to be working fine but if two DOSBox instances are linked together first and "Already connected" is selected in Setup program then the game hangs at startup screen after "V_Init: allocate screens" message.
4) The Need for Speed: Special Edition runs at single digit framerate in modem play.
Now, I know that non-gaming apps are not officially supported but the following could be symptoms of a bigger issue so I think it's worth looking into.
5) Issues with file transfer over modem connection (e.g. on BBS boards). No matter which protocol is used, the transfer starts throwing errors and then fails partway through.
6) If I connect to FTP server via modem (yeah, I know it's not the correct way to use FTP server but it's a good illustration of the issue) about 40% of the time commands arrive with garbage mixed in.
It kind of seems like modem's command/data buffer gets corrupted? None of this happens with null-modem emulation as far as I can tell. I have also tested multiple builds (latest SVN build, 0.74-3, 0.65, even DOSBox-X) and they all have these problems. According to the repo there have been no major updates to modem code since 2009 which would explain it.