Well, at 244 components, the Mega-One-8-One, is a mega PITA to assemble by hand, but it's done none the less. The Mega-One-8-One is a gate level replica of the 74181 Arithmetic Logic Unit (ALU), which was previously highlighted on hackaday.com ( Huge 74181 is a classic ALU you can actually understand!). Since the 74181 is not available new any more (yes you can get New Old Stock or NOS), I decided to build a replica for use in the DDL4-CPU so that the math and logic functions could be more easily understood. I originally had pins on the pcb near each input and output LED, but this didn't really lend itself to interfacing into a project, so I made a second revision of the design which included a 1x22 0.1" header that allows for the quick interface to the rest of the DDL4-CPU design...