It's a computer that uses the Z80 cpu. It can only run simple programs because it doesn't have any ram.
I got the idea from this guy:
https://youtu.be/CS44XJt_gYc
He explains how it works and he has a website with the assembly code and schematic.
http://nuclear.mutantstargoat.com/hw/z80micro/
i use this as the assembler:
http://clrhome.org/asm/
here is my assembly program:
.org $00
start:
ld a, 1
ld b, 10
left:
out (255), a
rlca
inc a
cp $ff
jr z, right
jr left
right:
out (255), a
dec a
rrca
cp $00
jr z, switch
jr right
switch:
djnz left
ld a, 0
incr:
out (255), a
inc a
cp $ff
jr z, decr
jr incr
decr:
out (255), a
dec a
cp $00
jr z, start
jr decr
