The programmable logic controller replaced relays and specialized control mechanisms with a programmable computer.

It was the first programmable computer, but it was electromechanical, rather than electronic, as it used relays for all functions.

Colossus was the world's first electronic digital programmable computer.

In other words, these consoles were single-purpose computers, not programmable computers; there was no software, only hardware, so no change of software was possible.

Some users of the terminals chose to use them as simple programmable computers instead.