It's worth discussing how all this works so you understand the challenges that are being overcome here. The ability to run multiple DOS programs at once is a pretty neat trick, given that this software heralds from an era of computing that was just barely ahead of what the Apple ][ was doing in 1978. If you want to skip this, go ahead. The root of the problem is that the IBM PCs basic architecture crystallized a very long time ago, in 1981. In a world where ten kilobytes of RAM counted for about...