The oldest emulated architecture?

[dsrtao]

The Z-Machine is the notional hardware that runs Zork and all the other Infocom text adventures, as well as thousands of interactive fiction games written since that time. There's never been a commercial hardware implementation, that I know of. (Some student projects, I think.)

There's a project to write a Z-Machine emulator for Android; there's already such an emulator for iPhone and PalmOS. ( http://code.google.com/p/twisty )

Is this the oldest architecture that still has people writing and running emulators?