This extract comes from a much longer piece on Jerry Neumann’s blog, Reaction Wheel. Highly recommended.
A Technological System is a set of technologies that interconnect as a platform to allow other innovations. When this system allows a fundamental and basic innovation, the system can cause a technological revolution.

For example, here is a group of some of the technologies involved in the start of the Railroad revolution. These technologies weren’t all invented at the same time, or even commercialized at the same time, but together they formed a system that made railroads viable. This diverse group of technologies included the high-pressure steam engine, precision machine parts, and improved metallurgy to allow rails to be cast. There were also innovations that we often don’t think about as technologies–things like corporate limited liability and the stock market–that allowed the concentration of the massive amounts of money needed to build the railway infrastructure.
The railroad was invented to solve a problem: moving coal from the mines to the piers, where it could be loaded on ships or barges. But the railroad addressed a broader and more basic need: moving things around quickly and cheaply. It did more than move coal from mine to ship, it moved goods from city to city, it moved mail from city to city, it moved people from city to city, and those people started living away from their hometowns en masse for the first time. These uses then enabled many other industries to flourish. This is the difference between a technological revolution and a plain old technological system: a technological revolution changes the whole economy.
Another constellation of technologies started the ICT revolution: semiconductors, integrated circuits, computers, software, computer networking, and mobile phones are some of them. Some of these together allowed the creation of the microprocessor. Originally built to power portable calculators, it ended up addressing another broad and basic need and started a new technological revolution.
An interesting thing about technological systems is that they are not just a bunch of technologies in the same place at the same time, they are systems: their further development is linked together. When some of the technologies in a linked system progress faster than others, the laggards become the limiting factor in the system. Thomas Hughes called these the ‘reverse salient’2 with all that implies. The system can not progress until the reverse salient is cured, so economic resources are directed to its improvement. The invisible hand detects what is holding progress back and redirects resources to cure it, so the system evolves faster than its individual technologies would. If you see a reverse salient, you have found a problem whose solution is far more valuable than it may first seem. Currently [2015], the most obvious reverse salient is battery technology.
Jerry Neumann’s Reaction Wheel Blog – The Deployment Age
Homework
What are the key components in the wider technological system that your innovation depends on?
What are the limiting factors (reverse salients), and what can you do about them?
See also:
The Onion
The Wrapper
Marks and Spencer as systems innovators
Business Model Canvas