For those of you who want to run your old PC MS DOS programs on Macintosh, there way to do just that. DOSBox can run DOS programs within the Macintosh environment. DOSBox can be downloaded for free at dosbox.com and there is a link to the program on the SchoolFreeware website. Schools and individuals can use DOSBox to run their old DOS software and games on their Mac. This tutorial shows how to get, install and use DOSBox.
DOSBox Download: DOSBox Manual: The link to OldDos (install file containing QBasic) is found here: Turbo Pascal 5.5 install files are found here.
QEMU and FreeDOS make it easy to run old DOS programs under Linux.