It’s mathematics!..............
My first was a MITS ALTAIR. Mrs. C shipped it to me while I was stationed in a wonderful southwest Asian locale. Soldered it together, hooked it to a model 45? teletype and it typed an ampersand on the paper(or was it a pound sign). 100 baud current loop, more or less morse code. Billy’s less interesting brother Jimmah was POTUS then.
We left it at the embassy. Back home I bought a SWTPC kit and started over in the Motorola world, 6800 then 6809. FLEX was the OS for those machines.
Back then KILOBAUD was the magazine to read. There are several dozen of them at the place in Ennis.