The midseventies SHARE survey 68

I'm sure one reason for those 360s hanging around so long when faster-better-cheaper alternatives were available was a result of the same mind-set. A perfect example of how rulesets crafted to encourage thriftiness and efficiency can actually produce the opposite. The problem is the decision-makers are ignorant of the environment. It makes sense to hold onto stable technology like tractors or washing machines for 10 years. Clinging to obsolete computer technology, especially expensive mainframes, is stupid financially and otherwise.

Another, hidden reason for the longevity of the 360s is that many of them were leased from leasing companies who took advantage of IBM's high rental rates to offer IBM hardware for less per month than IBM charged for the same thing. In order to make their money back they had to extend the life of each 360 out to 7 years, versus the 5 that IBM used to set their monthly rate. It was rare for an end user to purchase a machine back then, nearly all these systems were rented at

That's also one of IBM's major motivations for quickly replacing 360s with 370s -- it screwed the leasing companies big time. IBM hated the leasing companies -- they competed against Big Blue using IBM's own products.