Built my first PC in 1975 (same year Bill Gates and Paul Allen started Microsoft), after reading about a kit in that year's Popular Electronics magazine. I built the next kit available after the one Bill & Paul first built (an Altair). My kit was an Imsai 8080. All parts had to be soldered to the motherboard, along with all the LEDs and switches on the front panel. 64 memory chips in all.

No video monitors existed for PCs back then. Most of us used the ASR-33 teletype as our "console". It used punched paper tape for storage. If you wanted software, you wrote it yourself in machine code. I bought Bill's first program, MS-BASIC, 24KB on a fat roll of paper tape. I had the first or second PC in my county. And no pre-built PCs existed then, only those 2 kits.

There was no BIOS or other firmware chips. You booted the Imsai 8080 by entering a few lines of startup machine code - setting the left 16 switches, then hitting a switch to store that in the one of the Intel 8080 registers and repeating the process.

The ASR-33 teletype had a serious "carriage return"! It rang a bell and made a big bang. The floor shook and my house-mates would not let me compute after 10pm.