Standardization and decreased differentiation lower the switching or exit cost from any given vendor, increasing purchasers' leverage and preventing lock-in.
At some point, the number of discrete systems in a cluster will be greater than the mean time between failures (MTBF) for any hardware platform[dubious – discuss], no matter how reliable, so fault tolerance must be built into the controlling software.
When the first general purpose microprocessor was introduced in 1971 (Intel 4004) it immediately began chipping away at the low end of the computer market, replacing embedded minicomputers in many industrial devices.
With the development of the VisiCalc application in 1979, microcomputers broke out of the factory and began entering office suites in large quantities, but still through the back door.
These traditional designs were limited by speed-of-light delay issues inherent in any CPU larger than a single chip, and performance alone began driving the success of microprocessor-based systems.