Z os emulator
( February 2014) ( Learn how and when to remove this template message) Unsourced material may be challenged and removed. Please help improve this article by adding citations to reliable sources. This section needs additional citations for verification. For example, a group of developers independent of the Hercules project implemented a hybrid mainframe architecture which they dubbed "S/380" using modifications to both Hercules and to freely available classic versions of MVS (and later VM and DOS/VS), enhancing the operating systems with some degree of 31-bit (and as of 2016, 64-bit) binary compatibility with later operating system versions (and as of 2018, 32-bit is also supported). The open source nature of Hercules means that anyone can produce their own customized version of the emulator. Most of the skills acquired when exploring classic IBM mainframe operating system versions are still relevant when transitioning to licensed IBM machines running the latest versions. There is also a large community of current and former mainframe operators and programmers, as well as those with no prior experience, who use Hercules and the public domain IBM operating systems as a hobby and for learning purposes.
#Z OS EMULATOR PORTABLE#
Hercules can be used as a development environment to verify that code is portable (across Linux processor architectures, for example), supports symmetric multiprocessing (SMP), and is 64-bit "clean."
Mainframe Linux distributions include SUSE Linux Enterprise Server, Red Hat Enterprise Linux, Debian, CentOS, and Slackware. Several distributors provide 64-bit z/Architecture versions of Linux, and some also provide ESA/390-compatible versions. They run well on Hercules, and many Linux on IBM Z developers do their work using Hercules. There is no known legal restriction to running open-source operating systems Linux on IBM Z and OpenSolaris for System z on the Hercules emulator.The Michigan Terminal System (MTS) version 6.0A has been tailored to run under Hercules.However, a complete demonstration version of MUSIC/SP, packaged with the alternative Sim390 mainframe emulator, is available. Some of MUSIC/SP's features, notably networking, require z/VM (and thus an IBM license). The MUSIC/SP operating system may be available for educational and demonstration purposes upon request to its copyright holder, McGill University.
#Z OS EMULATOR SOFTWARE#
#Z OS EMULATOR LICENSE#
Operating systems which may legally be run, without license costs, on Hercules include: IBM's Coupling Facility control code, which enables Parallel Sysplex, and UTS also require licenses to run. Newer licensed operating systems, such as OS/390, z/OS, VSE/ESA, z/VSE, VM/ESA, z/VM, TPF/ESA, and z/TPF are technically compatible but cannot legally run on the Hercules emulator except in very limited circumstances, and they must always be licensed from IBM. However, many mainframe operating systems require vendor licenses to run legally. Hercules is technically compatible with all IBM mainframe operating systems, even older versions which no longer run on newer mainframes. There are two exceptions: Hercules uses hardware assists to provide inter-processor consistency when emulating multiple CPUs on SMP host systems, and Hercules uses assembler assists to convert between little-endian and big-endian data on platforms where the operating system provides such services and on x86/ x86-64 processors.
Its developers ruled out using machine-specific assembly code to avoid problems with portability even though such code could significantly improve performance. The emulator is written almost entirely in C.