Hercules

What Hercules is

Hercules is free, open-source software that emulates IBM System/370, ESA/390, and 64-bit z/Architecture mainframes. It lets a PC execute programs designed for those systems and represents mainframe I/O devices using PC devices, including DASD files and local tn3270 sessions. Hercules does not include an operating system, so users must provide one or run a standalone program. It can run systems such as z/OS, z/VM, z/VSE, OS/390, VM/ESA, and VSE/ESA when they are legally licensed. Features include dynamic reconfiguration, an integrated console, interpretive execution, snapshots and restore, and debugging tools. Guest TCP/IP networking can connect to the host through TUN/TAP and hercifc; multiple Hercules instances can also share devices through client and server instances. The host operating system list includes Linux, Windows, Solaris, FreeBSD, and Mac OS X. The project provides source archives and Windows installer and binary packages. It is licensed under the Q Public Licence. Its FAQ says it has not claimed production capability and describes its intended role as a system programmer’s toy. Documented unsupported features include ESCON, FICON, PR/SM, coupling links, and several z/Architecture facilities.