Hercules is an open source software implementation of the mainframe
System/370, ESA/390 and z/Architecture hardware. The Hercules
emulator runs under Linux on several hardware platforms including
the Intel Pentium PC, under Windows XP, Windows Vista, Windows 7,
Windows Server 2003, Windows Server 2008, Solaris, FreeBSD and under
MAC OS X 10.3 and later.

With the Hercules Emulator, your PC can emulate an IBM mainframe
processor. The mainframe can range from a 360 to a z10 running in
System/370 mode, ESA/390 mode or z/Architecture mode. Hercules
executes S/370, ESA/390 and z/Architecture instructions and channel
programs. It emulates mainframe I/O devices by using PC devices.
As an example, 3390 DASD devices are emulated by large files on the
hard disk of the PC and local 3270 screens are emulated by tn3270
sessions. Please note that not all 370 and 390 features have been
implemented.

Hercules only implements the raw S/370, ESA/390 and z/Architecture
instruction sets, it does not provide any operating system facilities.

You may use IBM programs and operating systems which have been
placed in the public domain.

Available IBM operating systems including OS/360, DOS/360, DOS/VS,
MVS 3.8, VM/370, and TSS/370.

Michigan Terminal System (MTS) is also available.
