Core Memory of the Whirlwind Computer

it’s the Soul of a New Machine — from the fastest computer in 1951.

As a core memory collector, I flocked to it on my whirlwind tour of the Computer History Museum storage archives.

Built by MIT for the U.S. Navy, the Whirlwind computer pioneered the use of core memory — the floating central stack here, ensconced like an altar to the magnetic magic within. The entire memory block was just 2KB, a vertical stack of 17 planes (16 bit word + 1 parity bit) of 1024 bits each. (More photos below)

The memory is non-volatile and may still hold the program from its last use. The memory took two months to weave by hand. From this proof of efficacy, core memory became the industry standard for random-access memory from the 50’s to the early 70’s, eventually replaced by semiconductor chips.

Whirlwind was the first computer capable of real time computations. It could add two 16-bit numbers in two microseconds and could multiply them in twenty microseconds. It took $8M and 8 years to build. It weighed over 9 tons and consumed over 100kW with 5000 vacuum tubes for logic. It was also the first to use a CRT for data output, and it used a light pen for input (to select symbols on the screen).

P.S. Here are the photos of my core memory collection, when you could see literal bugs in the RAM. 🙂