Computing · 1956

Hard disk drive

Fifty spinning platters offering random access to 5 million characters.

IBM's 350 disk storage unit for the RAMAC 305 held 3.75 MB on fifty 24-inch platters and weighed about a tonne. Areal density has since risen by roughly a billion times.

See it in the living tree Wikipedia

Arcs above join it to what it stood on, arcs below to what it led to. The bar places this stretch on the tree's whole timeline.

What it built on 1

Magnetic tape data storage 1951

What it led to 2

Relational model 1970
First black hole image 2019

Related measurements

The dashed line marks when it first worked.

Cost of memory and storage Latest: Memory: 1.09k $/TB (2023) Source: Our World in Data

Computation per constant dollar, 1850-2006 Latest: 7.3B million units of computer power per 2006 $ (2003) Source: Nordhaus 2007, Two Centuries of Productivity Growth in Computing, J. Econ. Hist. 67(1), Table 6