Is it possible to install a Macintosh operating system onto my PC? What prevents the install from completing? How does the operating system know whether or not it is an Apple machine?

Beyond a version specifically designed for PCs or some sort of low-level emulator, it is impossible I would imagine.

Any program designed to run on Apple computers is programmed for RISC processors (Apple), which is 100% imcompatible with CISC processors (PC)... In essence, it is impossible for an Apple setup program to actually execute on a PC without emulation. Your processor would not understand the instructions.

Something else that might keep you from installing it is that Apple uses a different CD file system (HFS)... Meaning you probably can't read it through Windows, or DOS (never tried though). The Mac OS setup would be the only way to read HFS aside from sort of special filesystem support from another program...

Also, the boot loader used in Apple CDs is totally different from PC CDs EVEN IF PC processors could execute the instructions to boot from the CD.

So I don't think you'd be able to install it in Windows OR outside of Windows.

there was at one time an idea for an OS called Rhapsody that was like NT for a MAC that would also run on a PC but it was never released....

What OS do you need? There are many mac emulators out there, all of them can emulate Motorola 68k, so getting an older version of Mac OS running at decent speed isn't a problem at all. I think there was a PowerPC capable emulator out there too, so theoretically you could run Mac OS X or Mac OS 9 too (The speed would be so amazing that unless your computer kills itself, you will ).

Check Computers->Emulators->Apple->Macintosh in Google directory.

BTW, Basilisk II is my favourite (I haven't tried the alternatives in a year or so, the competition may have improved by now)

if you need to read HFS volumes on PC hardware, BeOS can read them... could theorethically burn an ISO 9660 install CD, but it still won't work.... but if reading and writing Mac files is all you need, Be can do all that

A more precice reply:

No, it is not possible to install a Mac operating system on a PC.

Installation can't even start, because the executable files contain machine code for Motorola/IBM CPUs which have instruction sets completely different from i386 architecture.

OS can't even start detecting your machine. Your PC will crash on the first few instructions read from boot loader, assuming that BIOS will be able to even recognize the medium you are trying to boot from.

The only way to run a Mac OS on a PC is through an emulator (see my previous post).

There are some programs out there that let you explore HFS volumes, read Mac CDs, access Mac documents.