The Hercules System/370, ESA/390, and z/Architecture Emulator Hercules is an open source software implementation of the mainframe System/370 and ESA/390 architectures, in addition to the new 64-bit z/Architecture. Hercules runs under Linux, Windows (98, NT, 2000, and XP), Solaris, FreeBSD, and Mac OS X (10.3 and later). Hercules is OSI Certified Open Source Software licensed under the terms of the Q Public Licence. Hercules was created by Roger Bowler and is maintained by Jay Maynard. Jan Jaeger designed and implemented many of the advanced features of Hercules, including dynamic reconfiguration, integrated console, interpretive execution and z/Architecture support. A dedicated crew of programmers is constantly at work implementing new features and fixing bugs. This application can only be executed from the command line, but you can install the HercUI wrapper for a simple UI.