@MartyFouts >The idea of freely sharing source code dates to the 1950s, perhaps earlier
It was a thing ever since it was possible to have source code, which dates earlier than the 1950s.

>proprietary source was treated as trade secrets and just as inaccessible as it is now. >proprietary source was treated as trade secrets and just as inaccessible as it is now.
Indeed - but I decided not to mention that, as it adds much more complexity.

Back then computers regularly used a different instruction set per model, so to use the software you needed the source code - companies making their software difficult to get a copy of didn't necessarily make it proprietary - although a company refusing to provide a copy without the signing of an NDA would make it proprietary (but that only restricted people who betrayed humanity by signing the NDA).

>To get it, you had to sign a contract that prohibited you from redistributing it.
The "official" way to get it required a NDA, but there were also numerous other ways to get it that didn't require signing a NDA (i.e. a NDA-free version of "A Commentary on the Sixth Edition UNIX Operating System") and those copies were free before 1980 (too bad in 1980 such copies suddenly became nonfree).

>Such contracts were routine before copyright laws changed to allow software copyright.
Many evil companies routinely demanded NDAs, but not all of them did.