ENIAC was the first instance of what?

Answer:The answer is "computer".Explanation:The full form of ENIAC is "Electronic Numerical Integrator and Computer". It was the first computer, that uses circuits, and vacuum tubes.  It was the first thermonuclear weapon for feasibility study, which is specially used to calculate ballistic research for heavy weapons firing tables. It will take a large space to set up the system, that's why it is not counted in desktop computers.

ENIAC - Electronic Numerical Integrator And Computer - was the first electronic general-purpose computer.