🖥️VM/370 CE Brings 1970s IBM Mainframe OS to Docker in 2025

Your old mainframe skills just got a free sandbox

Somebody took IBM's VM/370 operating system, applied years of fixes and improvements on top of the last release IBM shipped without a restrictive license, and called it the Community Edition. You can now run a real mainframe environment on a laptop. Why should you care? Because the easiest path is a Docker container, with Podman as a drop-in alternative. If you've ever wondered how virtualization looked before containers ate the world, this is a hands-on way to find out. It's also a clean sandbox for learning CMS, CP, and EXEC scripting without touching production hardware. The numbers are modest on purpose. It runs on a single CPU with 16M of memory, and it's based on VM/370 R6 but adds features R6 never had. The default CMSUSER password is CMSUSER, so change it before you get cute. It ships with BASIC and a couple of FORTRAN programs to play with out of the box. Worth watching: if you want real hardware, eBay and local IT asset disposal companies are where used mainframes surface. Spoiler: you'll also need 3270 terminal emulation, because these screens don't scroll.