Thanks to the Hagley Museum and Library, we now have the manual online for Weisbecker’s earliest known microprocessor prototype, System 00, available on the Publications > Books & Papers page. (We recently published photos of System 00 in the Gallery.)
System 00 dates back to about 1971 and was built with standard 7400-series TTL chips. The manual documents system architecture, opcodes, machine operation, and even includes schematics and sample programs. Let me know if you build one!