Iterative Test Driven Development circa 1968

A crisis in software engineering came about in the late 1960s from the marketing of a computer that was much cheaper to own and operate, the IBM 360 family of computers. Fred Brooks managed the development of OS/360 and Gene Amdahl was the architect. These computers allowed software to run on a range of computers which meant that the cost of development could be absorbed across many systems and many years. The software industry saw the opportunity to develop new systems but there was an insufficent number of experienced developers available to develop the software. Larger projects also required more intensive levels of management.

The 1968 NATO Software Engineering Conference was held three years after delivery of IBM's OS/360 that initiated recognition of a crisis in the realms of planning, scheduling and completing software. Brooks best illustrates the problem of scheduling by identifying "the mythical man-month" and illustrating it with a quote from another computer scientist: "while it takes one woman nine months to make one baby, nine women can't make a baby in one month".

At the 1968-69 NATO Software Engineering Conference an oddly familiar methodology was discussed:

SDLC and the waterfall methodolgy appear to be the worst possible way of addressing the the problem of scheduling a project and completing it successfully but, SDLC was adopted because it was the most easily communicated. The 'engineering' part of 'software engineering' became conflated with SDLC.