This programmable electronic calculator uses some 1400 electron tubes; its weight is more than 600 kilograms. Instead of using a keyboard and screen, input and output was by means of punched cards. The punched card machine (almost the same size as the 604 itself) is not shown here.

The 604 was IBM's first step into the realm of electronic computers, and at the time had many innovative features. But it differs in so many ways from modern calculators (speed, size, ease of use, reliability, price...) that you can hardly compare them.