The Edsac was the first computer to run in Cambridge and was the first machine in the world to provide a computing service. It was designed and build under the leadership of Maurice Wilkes and successfully ran its first program (to print squares) on 6 May 1949. The files in this distribution provide an interactive simulator of the Edsac as it was in 1949. This simulator is implemented in BCPL but can be run directly on Pentium based Linux system since a suitable executable has been provided.

Some documentation can be found in README file.

Engraved on the glass surrounding the first floor coffee lounge in the Computer Laboratory (in the Williams Gates Building) is some five track paper tape of Edsac's initial orders and a program to print the squares and differences of the numbers 1 to 100. These tapes are explained in a poster next to the glass which can also be viewed by clicking on edsacposter.pdf.

An annotated recording of a console session demonstrating the Edsac simulator and, in particular, the execution of the initial orders loading and executing the squares program can be viewed by entering the Cintpos system and executing the command: playback records/edsac.rec

To obtain a copy of the Edsac simulator, click on edsac.tgz. or edsac.zip.

Right click on the link then select the menu item "Save Target As...", but be aware that your browser may (silently) decompress the compressed file. So edsac.tgz may arrive as a .tar file, in which case it should be decompressed using: "tar xvf edsac.tgz" rather than the more normal "tar zxvf edsac.tgz".

The sizes and dates of creation of these files can be found in FILES.


This distribution is newish and probably contains bugs.

My home page.

Martin Richards, updated 29 May 2009