Since then, I have accumulated current events and material from a number of historical sources into this chronology. Some entries are lengthy - e.g. I geenrally give all the specific details available about early machines. Others are fairly brief. Cross references between dates are given for some specific topics, but the chronology is best searched on a computer. The dates have been acquired from many sources and some may be wrong.
Older dates are usually only approximate, sometimes only educated guesses.
I have included many 20C dates because these are not readily available. However, there is often disagreement about these dates because there is disagreement about what was actually the first of something and because any given project was spread over some years. I have tried to use the most authoritative date. Computing devices also owe a historical debt to mechanical devices, particularly automata. I have mentioned the more notable and more recent examples.