core=normal
.debug
.debug sierra.exe
. DOSBox will pause here while waiting for aThis plugin has not been tested on many platforms, but it has been reported to work with 32-bit IDA 6.9 Starter, on 32-bit Windows (using MSYS2), 64-bit Linux, and 64-bit Mac OS X.
The debugger plugin will rebase the program to match the memory location in DOSBox, but there have been many bugs with this in older versions of IDA. If this is causing problems, try manually rebasing before starting the debugger, or even recreating the database at the right offset.
There is a known bug with breakpoints on the program entry point. As a workaround, you can use the "Suspend on debugging start" option in IDA if you wish to break on starting the process. Breakpoints at other locations should work fine.
With a 32-bit IDA, you will have to build a 32-bit dosbox, even on 64-bit platforms.
And finally, patches to improve the plugin are most welcome!