IBM 704

IBM 704

The IBM 704 is the machine programming languages grew up on. Introduced in 1954 — designed by John Backus and Gene Amdahl, two names that would each reshape computing again — it was the first mass-produced computer with hardware floating-point arithmetic, added index registers and magnetic-core memory to the 701's bones, and could run 12,000 floating-point additions per second. IBM built 123 of them.^[1]

Its software firsts are unmatched by any single machine before or since:

• FORTRAN — Backus's team built the first optimizing compiler for this machine in 1957, on the bet that generated code could approach hand-coded performance; the win ended the "real programmers use assembly" era.
• LISP — McCarthy's language first ran on a 704; the machine's two 15-bit address fields inside a 36-bit word are literally why lists still have car and cdr — the fields were the Contents of the Address/Decrement parts of the Register.
• MUSIC — Max Mathews developed the first computer music program on a 704, the ancestor of every synthesis toolchain since.
• SAP — the SHARE Assembly Program, the assembler the SHARE user group distributed to every 704 shop.

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Science's workbench

The 704 was also where computation met its early flagship problems: Ed Thorp derived his blackjack theory on one in FORTRAN; MIT's 704 tracked satellites for the Smithsonian's Operation Moonwatch in 1957; and Frank Rosenblatt implemented the first Perceptron — the ancestor of every neural network — on a 704 at Cornell Aeronautical Laboratory that same year. NRL ran Vanguard rocket flight dynamics on one; Los Alamos ran an early batch monitor called SLAM on theirs.^[3]

Where it sits

The 704 is the pivot where "the machine" and "the software" start negotiating — hardware floating point and index registers made FORTRAN practical, and FORTRAN made the machine immortal. Between the machine everyone could afford and the 709/7090 flagships, it's the one the high-level language was born on — twice.

Check your understanding

• Who designed the 704 — and what two things did they each go on to change?
• Which two landmark languages first ran on the 704?
• Where do car and cdr come from?
• What two non-language landmarks ran on the 704 (music, AI)?