• women were assumed to be working for a few years before marriage and not supporting a family
  
• so there was no way to promote them (except perhaps to supervisor of the computing pool)
• Women computers did more complex calculations, often using adding machines

In WWII in England women were drafted into war work

War timeline:

• Sept. 1939: Hitler invades Poland, Britain and France declare war
• Mar. 1940: code breaking using electromechanical computers begins at Bletchley Park
  
• May 1940: Hitler invades first Denmark and Norway, then Holland and Belgium
• June 1940: Germany occupies France, leaving England to fight alone
• Dec. 1941: Pearl Harbor, US enters the war
• Dec. 1943: Colossus completed
  
• May 1945: victory in Europe
• Aug. 1945: atomic bombs dropped on Japan, Japan surrenders a week later
• Nov. 1945: ENIAC (first US electronic computer) completed
  

women were 80% of workers at the intelligence center at Bletchley Park

• women wrote down and typed up coded messages from German radios (encrypted morse code)
  
• those messages were fed into electromechanical machines called Bombes that tried different code possibilities (this was Turing's key contribution)
  
• they helped crack the Enigma code, but the Germans went on to more complex codes such as Tunny
• mostly electromechanical machines to crack those codes were very unreliable
• the Colossus Mark I machine in Dec. 1943 was much more effective; much faster and more reliable, doing calculations electronically with vacuum tubes
  
• Colossus Mark II in 1944 was even faster
• women who worked as registrars prioritized and scheduled the work
• even skills like typing were as important to doing the work quickly as skills of the cryptographers
• you can't do the job without people doing the most routine work
• the people who were operating the machines were not just doing routine work but doing part of solving the problem
• solving the problems of keeping the machine running
• setting up the machine for the particular problem--programming
  
• after the war women were pushed out of many jobs but did continue to be computer operators operating Hollerith machines
• the Civil Service still required women to resign their jobs when they married until 1946 (though they could be re-hired as low paid temporary workers)
  

• ENIAC was general purpose but was mechanically programmed
• Colossus was special purpose (code-breaking), also mechanically programmed, completed sooner
• Britain kept Colossus secret until the mid 1970s while ENIAC was publicized in Jan. 1946

note descriptions

• "machines operated around the clock" but not without operators
• did women tend the machines or operate them
•