Closed vs. open source timeline.

[Andrew Back]

So whilst the GNU project was announced in 1983 I've heard many examples 
being cited of the source to software being shared prior to this, E.g. 
IBM's VM up to vN.N. And indeed recall reading somewhere that up until a 
certain point in time the source to most if not all software was 
available. As vendors made their money from hardware sales and you were 
unlikely to be able to buy a clone or build a machine yourself, and so 
safe-guarding source code was not a major concern.

Does anyone know if the history of closed/unavailable vs. open/available 
source is documented anywhere? Ideally in a book or journal that can be 
properly referenced.

Regards,

Andrew

----------------
Andrew Back
a at smokebelch.org