Platform and Community Observations from a Mainframe Software Pioneer "We so often trace our antecedents back simply to the Unix heritage, or the Lisp hacker heritage. But when I've talked to IBM old-timers, they make clear just how many of the social dynamics and collaborative software development paradigms of the early mainframe era resemble the open source tradition."
I've been reading From Airline Reservations to Sonic the Hedgehog : A History of the Software Industry which describes the early history of mainframe development. A group called SHARE whose only qualification was that they were the owners of the new 704 IBM mainframe. In it's first year of operation they claimed to have saved members around $1.5 million dollars (1950s dollars) and had shared around 300 programs.
The development of FORTRAN apparently created a "network effect". Users made an investment in FORTRAN because it was the first reliable language (increasing programmer productivity by 5 to 10 times). This was quite impressive as up to three quarters of the cost of running a computer (staff and machine time) was taken up writing programs - not running them. This led to other manufacturers providing FORTRAN for their machines and users sharing code amongst each other. Programs were considered free - they had no intrinsic value.