IBM's 'Programmer's Reference Manual' for FORTRAN (Formula Translation) reached engineers and scientists, marking one of the earliest high-level programming languages ever distributed. Developed by a team led by John Backus, FORTRAN let programmers express calculations in near-mathematical notation rather than laborious assembly code, cutting development time dramatically and helping trigger the software industry as we know it.
Before FORTRAN, programming a computer meant writing in machine code or assembly, an exacting and exhausting process where a single misplaced instruction could send hours of work to waste. John Backus convinced IBM management to fund a small team to build a compiler that could translate ordinary algebraic notation into efficient machine instructions, a proposition many engineers at the time considered close to impossible.
Skeptics doubted a compiled language could ever run as efficiently as hand-tuned assembly code, which was the coin of the realm for scarce, expensive computer time. Backus's team spent over two years engineering a compiler clever enough to produce code nearly as fast as a human expert's, and largely succeeded.
The manual distributed to early users of the IBM 704 opened programming to thousands of scientists and engineers who had no interest in learning assembly. FORTRAN's influence rippled outward for decades; variants of it are still used today in high-performance computing, weather modeling, and physics simulations, making it one of the longest-lived pieces of technology in computing history.