The very first thing I owned that was supposed to be a computer, but never really worked,
looked something like this,
although no actual pictures of it exist anymore:
(open the picture in a new windows to see it full scale)
Actually I never progressed beyond building the memory system, (256 bytes using eight 2102 RAM chips)
I could load the RAM with a bunch of toggle switches, and read out with LED"s, I planned to add a CPU next, but it never happened, instead I did help build an older friends Z80 system. Built from scrap on wire-wrapped eurocard boards with a backplane, but mostly copied after the Exidy Sourcerer
I ported a BASIC interpreter I found the sourcecode of in a German magazine for it, and did a lot of wire-wrapping, the boards actually were home brewn, single sided PCB's, with only power and GND traces, the rest of the connections were wire-wrapped.
with a tool like this:
. In the end this nameless computer worked well, and could draw nice "highres" (512x240) pictures in monochrome.
The first working
computer I myself owned was a KIM-1.
Actually it also wasn"t really a computer, but more a development board, (not unlike the R-PI) but it used a 1MHz 6502 microprocessor, with 1K RAM. No HDMI (or any video output) in sight, it used six 7-segment LED displays. Input was a hex keyboard. I built a "glass teletype" for it, which gave it a 40 x 16 video display.
My next (first real) computer, after the KIM-1 was built from a kit, it was the LNW-80 a TRS-80 clone (with high resolution color graphics). I added two 5 1/4" floppy disks, with NEWDOS80.
P.S. Post edited, when the pictured didn't work anymore, and appended it somewhat, one of the perks of being a moderator.