The Hercules System/370, ESA/390, and z/Architecture Emulator
SDL Hercules 4.x Hyperion
This is the official web page for the SDL 4.x version
of the hercules-390 mainframe emulator, code named "Hyperion".
Hercules was created by Roger Bowler. Jay Maynard (“the Tron Guy”) was the maintainer from 2000 to 2012. 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.
Please Note that this version of Hercules is only called the "SDL" version in order to distinguish it from any other versions of Hercules that may be out there, and not for any other reason. This version of Hercules was neither created by, nor is owned by, nor maintained or supported by Software Development Laboratories. Hercules it not the work of any one person. It was created by many very smart and talented individuals over the course of many years. For a list of just some of these many very talented people, please refer to question 6.01 of our FAQ.
Hercules is OSI Certified Open Source Software
licensed under the terms of the Q Public Licence.
What people are saying about Hercules
Never in my wildest dreams did I expect to see MVS
running on a machine that I personally own.
Hercules is a marvelous tool. My thanks to you all for a job
very well done.
I do miss my mainframe a lot, and playing with Herc sure brings back
memories. Just seeing the IBM message prefixes, and responding to
console messages again was a wonderful bit of nostalgia!
I have installed your absolutely fantastic /390 emulator.
You won't believe what I felt when I saw the prompt.
Congratulations, this is a terrific software.
I really have not had such a fascinating and interesting
time on my PC lately.
Such simulators have been available for a long time. One of the most
complete (up to modern 64-bit z/Architecture) is hercules.
An apparently excellent emulator that allows those open source
developers with an "itch to scratch", to come to the S/390 table
BTW grab a copy of Hercules and you can test it at home.
It's a very good S/390 and zSeries (S/390 64bit) emulator..
It works even better than I imagined.
Hercules is a fine piece of software!
Hercules is a systems programmer's dream come true.
Aside from the electric trains my parents got
me in 1953, this is the best toy I've ever been given,
Congratulations to you and your team on a fine piece of work!
Congratulations on a magnificent achievement!
For anyone thinking running Hercules is too much trouble or too hard
or whatever, I came home from work one day and my 13 year old 8th
grade son had MVS running under VM under Hercules on Linux. He had
gotten all the information about how to do this from the Internet.
When he complained about MVS console configuration and figuring out
how to get it to work with VM, I knew he had felt all the pain he
ever needed to feel about mainframes.
I am running a fully graphical Centos z/Linux environment on my desktop.
The Hercules emulator is an amazing feat of engineering.
I just wanted to send my compliments to the team for an excellent job!
Thanks much for making this product part of the open-source community!
I have DOS and DOS/VS running on Hercules with
some demo applications, both batch and on-line. It does bring back
some good memories. My compliments go to the Hercules team. Thank you.
This is stunning piece of work. To say that I am blown away is an
understatement. I have a mainframe on my notebook!!!!!!
P.S. Now if I can just remember my JCL
NewsRead Hesh Wiener's Technology News article about Hercules at http://www.tech-news.com/another/ap200601b.html
Read Moshe Bar's BYTE.com article about Hercules at http://web.archive.org/web/20010712143133/http://www.byte.com/documents/s=429/BYT20000801S0002/
For eighteen months, the IBM Redbook SG24-4987 Linux for S/390 at http://www.redbooks.ibm.com/abstracts/sg244987.html contained a chapter written by Richard Higson describing how to run Linux/390 under Hercules. Then suddenly, all mention of Hercules was mysteriously removed from the online edition of the book! Read the story of the disappearing Redbook chapter at http://www2.marist.edu/htbin/wlvtype?LINUX-VM.25658
View the foils from Jay Maynard's presentation given at
SHARE Session 2880
in San Francisco on 20 August 2002
as a PDF file (815K) from
To find out more about this particular version of SDL Hercules 4.x Hyperion, follow these links:
What's New, Release Notes, etc:
Web documentation:The below web pages are, at this time, the only accurate source of documentation for SDL Hercules 4.x Hyperion.
PDF manuals: (obsolete)The below PDF manuals are for the original 4.0 version of Hercules Hyperion, not for SDL Hercules 4.x Hyperion. Most of what's contained within them should still be somewhat accurate however. Over time though, as more and more changes and enhancements are made to SDL Hercules 4.x Hyperion, they will gradually become less and less accurate. The official web documentation however, should always be accurate and thus authoritative.
Source code and binaries:
GitHub source code repository:
The complete source code to the current bleeding edge development version of SDL Hercules Hyperion is available via anonymous access to our git source code repository.
Please note that, as a bleeding edge development repository, it may contain faults (bugs) which may or may not be fixed at an unspecified later date, and might contain experimental code that may not appear in future releases.
Build instructions are contained in the source files BUILDING
and INSTALL (for Unix) or README.WIN64 (for Windows).
Fish also has a
"Hercules Windows Build Instructions"
web page on his SoftDevLabs web site.
Minimum supported host platforms:
If you have any questions or comments please consider joining the hercules-390 discussion group at groups.io.
Bug reports for SDL Hercules Hyperion (together with your diagnosis of the fault, please!) should be entered into our Github issue tracker (preferred):
Other Hercules-related sites
IBM, System/370, ESA/390, and z/Architecture are trademarks or registered trademarks of IBM Corporation. Other product names mentioned here are trademarks of other companies.