Qemu
I just recently discovered qemu·, and the result is that I’m a happy camper. I’m preparing for the Bar Exam using antiquated software from MicroMash·, the “other” bar prep company (cf. Barbri·, at about twice the cost). The program is basically a Visual Basic quiz application written originally for Windows 3.1 and updated slightly in the intervening time (the questions, of course, are entirely up to date to current law). It’s not a bad system—it tracks your progress as you go, and feeds you questions in the areas where you need to focus.
Obviously, there is no GNU/Linux version of the program. Less obviously, but perhaps predictably, the program doesn’t run under WINE· either. I’ve found that new, highly complex software like Microsoft Office XP works much better under WINE than old, very simple programs like this quiz program. There was also no easy way to extract the questions so that they could be presented by some other Linux-native software.
Enter qemu, a virtual machine emulator included in Debian·. With qemu, I can run a full-fledged Windows 98 box (or any other version of Windows that I might own) in a window on the Linux X desktop, and the bar prep program runs fine. Because my laptop is pretty fast, the resulting system is faster than any Windows 98 system I ever had in my Windows days, despite the emulation layer. Network and sound work as well. I had previously tried this on bochs, a similar emulator, but it was painfully slow (I think there are other advantages to bochs).
Plus, no worry about viruses and other forms of Windows pestilence, since the whole system is contained within a single file. Backup or “snapshot”? Just copy the file. Want to take a break? Just pause the whole machine. It’s all quite clever.
qemu is also in various stages of emulating several other common processors, including the PowerPC, so someday you could run Mac OS X Panther (or Jaguar, or whatever they call it), on a GNU/Linux system on a commodity PC… Even, say, an XBox·.
It strikes me that these sort of emulators are crucially important to the eventual world domination of linux. Just as today the only way I can run my old Commodore 64 software is with vice·, someday the only way to run the thousands of obscure Windows programs now extant will be with WINE and virtual machines like qemu and bochs.