Cosmac Elf
by Rob Howard
The COSMAC ELF was my first computer. I built it with a soldering iron in late 1976, when it was introduced in Popular Mechanics magazine for about $150 (or $850 in today's currency). It has 8 toggle switches to enter a single byte, and your code had to fit in 256 bytes - no "K" or "M" or "G" prefixes - just bytes. An iPhone 15 has a billion times more memory.
The version I had contained a newer hex keypad, like this:
I still remember my first program ever written when I was 12 years old:
7A 3F 00 7B 30 01
It turns on the on-board led light.