History of Control Language (CL)

CL isn’t unique to the AS/400 - it has evolved with the platform, and it has never been replaced.

CL is the same language across AS/400, iSeries, System i, and modern IBM i - but it has grown more powerful over time. Old CL code still runs perfectly on today’s IBM i systems, and new CL features continue to be added.

How CL Has Evolved Across the Platforms

AS/400 (late 1980s–1990s)

  • This is where CL as we know it really solidified.
  • Classic commands, classic syntax, and the foundation of the language.

iSeries (early 2000s)

  • Still used the same CL from AS/400.
  • IBM added new commands and enhancements, but everything remained backward‑compatible.

IBM i (2008–today)

  • Fully supports all AS/400 and iSeries CL programs.
  • Adds many new commands, functions, and modern features that older systems never had.
  • CL continues to be actively developed and expanded.

So is old CL different to new CL?

No - but also slightly YES 😉

  • The core language is the same.
  • Old CL runs unchanged on new systems.
  • New IBM i CL includes features that won’t run on older hardware.

Think of it like English: You can still understand Shakespeare, but modern English has new words he never used.

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