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Sep 30, 2026 · Industry Insights

Gary Kildall's CP/M: The First PC OS That Lost to 'Plain Theft'

Gary Kildall created CP/M, the first widely adopted microcomputer OS with a hardware-abstracting BIOS layer, but after failed IBM negotiations, Microsoft cloned its API from Kildall's public manual to build MS-DOS, which Kildall called 'plain and simple theft,' leading to CP/M's decline despite its foundational influence on modern OS design.