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, Windows NT, and Windows 2000.

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.

Follow these links to find out more:

Download the current release version, 2.17.1:


The CVS version

The complete source code for the current development version of Hercules is also available via anonymous access from our CVS source code repository. The CVS root is CVSROOT=:pserver:anonymous@cvs.conmicro.cx:/usr/cvs/hercules. Doing a checkout on module "hercules" will get you the source for all of Hercules, and checking out "wingui" will get you the complete source for the Windows GUI front end (HercGUI).

No password is required; just press enter when asked:

cvs login
(Logging in to anonymous@conmicro.cx...)
CVS password:
cvs -z9 co hercules
cvs server: Updating hercules

Please note that this will get you the current development version of Hercules, which is not release quality and thus might not even work (since it's still under development). If you want the current, stable, release version of Hercules (i.e. one that is known to work properly), then use the previously mentioned links instead.

Read the file README.CVS for additional and updated instructions for building the development version.


What people are saying about Hercules

“ 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! ”
— Bob Brown

“ 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. ”
— IBM Large Systems Specialist

“ An apparently excellent emulator that allows those open source developers with an "itch to scratch", to come to the S/390 table and contribute. ”
— Mike MacIsaac, IBM

“ 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.. ”
— Alan Cox

“ It works even better than I imagined. Hercules is a fine piece of software! ”
— Dave Sienkiewicz

“ Hercules is a systems programmer's dream come true. ”
— René Vincent Jansen

“ Aside from the electric trains my parents got me in 1953, this is the best toy I've ever been given, bar none.”
— Jeffrey Broido

“ Congratulations to you and your team on a fine piece of work! ”
— Rich Smrcina

“ Congratulations on a magnificent achievement! ”
— Mike Ross

Read Moshe Bar's BYTE.com article about Hercules at 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://www.trustsec.de/deb390/print.php?sid=26

View the foils from Jay Maynard's presentation given at SHARE Session 2880 in Minneapolis on Wednesday, 25 July 2001.


Other Hercules-related sites

If you have any questions or comments, join the hercules-390 discussion group at http://groups.yahoo.com/group/hercules-390.

Bug reports (together with your diagnosis of the fault, please) may be sent to me, Jay Maynard, at jmaynard @ conmicro.cx.

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.

Last updated 12 February 2003