On April 19, 1957 researchers run the first FORTRAN program. Short for “FORmula TRANslator,” FORTRAN enabled computer programmers (“coders,” at the time) to work in a “high-level” language, greatly simplifying program writing. The first FORTRAN program (other than internal IBM testing) runs at Westinghouse, producing a missing comma diagnostic. A successful attempt followed.
Source: https://www.computerhistory.org/tdih/april/19/#first-fortran-program-runs
On April 21, 1988 Tandy Corp. holds a press conference in New York to announce its plans to build clones of IBM’s PS/2 system computers. The conference comes on the heels of IBM’s announcement that it would license patents on key PC technologies, a move that signaled its willingness to let other companies clone its machines. Within five years, IBM clones became more popular than original IBM machines themselves.
Source: https://www.computerhistory.org/tdih/april/21/#tandy-plans-to-build-ibm-ps/2-clones
On April 23, 1933 was born Annie J. Easley, an African-American computer scientist, mathematician, and rocket scientist. She worked for the Lewis Research Center (now Glenn Research Center) of the National Aeronautics and Space Administration (NASA) and its predecessor, the National Advisory Committee for Aeronautics (NACA). She was a leading member of the team which developed software for the Centaur rocket stage, and was one of the first African-Americans to work as a computer scientist at NASA.
Source: https://en.wikipedia.org/wiki/Annie_Easley
On April 24, 1945 was born Lawrence Gordon Tesler. He was an American computer scientist who worked in the field of human–computer interaction. Tesler worked at Xerox PARC, Apple, Amazon, and Yahoo! While Tesler was working at Apple, he worked on the Apple Lisa and the Apple Newton, and helped to develop Object Pascal and its use in application programming toolkits including MacApp.
Source: https://en.wikipedia.org/wiki/Larry_Tesler
On April 25, 1961 The US Patent Office issues Robert Noyce a patent for the integrated circuit, starting a long battle with Jack Kilby over who had rights to the patent. Kilby had invented a germanium version of the circuits, while Noyce developed the silicon integrated circuit — the one that grew to be more accepted. Integrated circuits replace transistors in computers, allowing the machines to be significantly smaller.
Source: https://www.computerhistory.org/tdih/april/25/#noyce-awarded-patent-for-integrated-circuit