May 6, 1949
EDSAC runs its first programs
On May 6, 1949, the EDSAC at Cambridge ran its first programs — including a table of squares written by Beatrice Worsley.
What it was for
EDSAC was among the first practical stored-programA design where instructions and data share memory — programs can be loaded and changed without rewiring hardware. computers, keeping both instructions and data in memory. That May day proved Maurice Wilkes's design worked end to end. Wheeler's Initial Orders — a built-in program that translated mnemonic instructions from paper tape — were already in place and would soon be recognized as the first assembler.
Why it's here
EDSAC's first successful run marked stored-programA design where instructions and data share memory — programs can be loaded and changed without rewiring hardware. computing working outside a lab prototype.
Why it mattered
It showed that programs and data could live in the same memory — the model every modern computer uses.
What it solved
Earlier machines like ENIAC were reprogrammed by rewiring; EDSAC loaded new tasks from tape into memory.
Media
ImageEDSAC at Cambridge (1948)Computer Laboratory, University of Cambridge. Reproduced by permission. CC BY 2.0, via Wikimedia Commons
Related
- EDSAC Initial Orders assemblerMay 1949
- ENIAC formally dedicatedFebruary 15, 1946