Hercules is an emulator for the IBM System/370, ESA/390, and
z/Architecture series of mainframe computers. It is capable of running
any IBM operating system and applications that a real system will run,
as long as the hardwre needed is emulated. Hercules can emulate FBA and
CKD DASD, tape, printer, card reader, card punch, channel-to-channel
adapter, and printer-keyboard and 3270 terminal devices.

Hercules information can be found on the web at
http://www.hercules-390.org/ .