Oh boy, M0E ... looks like I get the "old fart" award here...
My own first computer-like thing was a homebuilt "adder" using discrete 7400 TTL chips (AND, OR gates, and a latch).
It had 4 toggle switches, 2 push buttons, and 5 transistors driving 5 light bulbs. (And cost me probably $120)
It worked like this:
Power on, reset.
Press one button to enter a number,
enter 4 binary digits on the toggles for first number,
press the button again to enter second number,
enter 4 binary digits on the toggles for second number, and
press the button again to add and show result.
Then the light bulbs would light the resulting binary value.
(And the geeky trivia question: why were there FIVE light bulbs instead of four?)
The next thing, that really was a computer, was built on top of that last thing:
An 8080 microprocessor on a breadboard that had a whopping 128 bytes of memory, an address controller, some more latches and what not.
Eight switches for loading in the code (seriously), and a gob of transistors driving lamps to see what it was doing.
Needless to say, I never filled that code space - got tired of clicking switches.
The first REAL computer I worked on was and IBM 360 doing BAL Assembler ("Branch And Link") and FORTRAN
--- Using punch cards
(And the second geeky trivia question: what is the "Bit Bucket"?)
(Feeling Old and Somewhat Cranky)