Why were plugboards a problem for programming early computers such as ENIAC?

The use of plugboards in early computers like ENIAC presented a significant challenge because they made the machines extremely difficult to program.12

While plugboards allowed instructions to be read electronically—enabling the computer to run at high speeds rather than being limited by slower mechanical devices—the physical process of configuring them was highly inefficient. Specifically, it took days to manually rewire the machine for each new problem. This cumbersome requirement was such a liability that the system was only considered programmable with some generosity.123

This limitation was a primary motivation for the development of the stored-program concept, championed by John von Neumann and his colleagues. By storing instructions in the same electronic memory used for data, computers could access instructions as quickly as needed, eliminating the need for the time-consuming manual rewiring required by plugboards.14