The 8088 processor has different divide exception behavior than later Intel processors, and it is for this reason that MSFS v1.05 doesn't work correctly in DOSBox. There are actually a few quirks of the 8088 that DOSBox doesn't emulate; although some unofficial branches do, but I'm not sure if any get the divide exception behavior fully correct. Anyway, I've made workarounds for the few games affected by the quirks, including MSFS v1.05. The attached patch replaces the divide exception handler in v1.05 with the one from v2.13, which is less 8088-specific -- it generally works, but the demo mode appears sensitive to speed, so different things happen depending on cycles. Rename the image FS105.IMG, place the workaround program in the same directory as the image, and then run the program in DOSBox to patch the image.