From running the original (1979) to MVS 3.8j (“Turnkey MVS”), the hobbyist community relies on Hercules v4 for its reliability and extensive documentation.

While Version 3.07 had experimental z/Arch (64-bit), Version 4 completed and hardened it:

| Solution | Cost | Architecture Support | Ease of Use | Performance | |----------|------|---------------------|-------------|--------------| | Hercules v4 | Free | S/370, ESA/390, z/Arch | Moderate (text config) | Very good | | IBM ZD&T (zPDT) | Thousands $/yr | z/Arch only | Easy (pre-built appliances) | Excellent (native Linux KVM) | | FLEX-ES (Fundamental Software) | Commercial | S/370, ESA/390 | Moderate | Good | | RATL (Rare Animals on Linux) | Free (discontinued) | ESA/390 only | Difficult | Fair |

Ready to start?

The development team (led by “Fish” – David Edwards, and “Ivan” – Ivan Warren) is actively working on , which promises improved z/Arch paging and experimental support for IBM’s newer SIE (Start Interpretive Execution) instructions.