VMWare, the company whose Virtual Platform software was the toast of Demo 99 last week has been in touch with ComputerWire to tell us how it works. Virtual Platform lets users of one x86-based operating system run applications written for any other. The company was careful to point out that Virtual Platform is not an emulator, but didn’t provide many clues as to what it is, except to say that it sells for $299 and comes in two versions, for Linux and Windows NT. It’s sort of magic, says an apologetic Diane Greene, who is president of VMWare. Mendel Rosenblum, chief scientist, supplies more detail: One way to view this as different from a typical emulator is that when we run, we take total control of the machine, he explains. Virtual Platform doesn’t simulate an x86 machine. Instead, it lets the guest operating system talk directly to the hardware, bypassing the host OS. Radical though it sounds, Rosenblum says the approach has substantial performance benefits, especially when running CPU-bound applications. He estimates that software running on a guest OS on Virtual Platform slows down only 5% compared with the same software on a machine running the same OS. That’s about ten times the performance any emulator can hope to achieve, he says. Applications which swap between the host OS and guest OS and programs that require access to I/O ports take corresponding performance hits but still outrun emulators, the company claims. Having said that, Rosenblum is quick to defend developers of emulators like Connectix’s Virtual PC. For what they are, he says, they’re very good, especially when you take into account the fact that they are running on a different architecture. Nothing emulates an x86 processor like an x86 processor, he concludes. Diane Greene says that in spite of her early concern that people would misunderstand how the software works, she has been amazed by the reception afforded to VMWare and its Virtual Platform. The company’s new web site received 400,000 visits in its first live week. Many of those visitors registered to be notified of the beta.