Magic-1 is a completely homebuilt minicomputer.  It doesn't use an off-the-shelf microprocessor, but instead has a custom CPU made out of 74 Series TTL chips.  Altogether there are more than 200 chips in Magic-1 connected together with thousands of individually wrapped wires.  And, it works.  Not only the hardware, but a full software stack. There's a ANSI C cross-compiler for Magic-1 (retargeted LCC), a fully multi-user, multi-tasking port of the Minix 2 operating system. a TCP/IP stack and hundreds of programs.