mcpublic writes "When a small team of reverse engineers receives the blessing of a big corporate legal department, it is cause for celebration. For the 38th anniversary of Intel's groundbreaking 4004 microprocessor, the company is allowing us to release new details of their historic MCS-4 chip family announced on November 15, 1971. For the first time, the complete set of schematics and artwork for the 4001 ROM, 4002 RAM, 4003 I/O Expander, and 4004 Microprocessor is available to teachers, students, historians, and other non-commercial users. To their credit, the Intel Corporate Archives gave us access to the original 4004 schematics, along with the 4002, 4003, and 4004 mask proofs, but the rest of the schematics and the elusive 4001 masks were lost until just weeks ago when Lajos Kintli finished reverse-engineering the 4001 ROM from photomicrographs and improving the circuit-extraction software that helped him draw and verify the missing schematics. His interactive software can simulate an ensemble of 400x chips, and even lets you trace a wire or click on a transistor in the chip artwork window and see exactly where it is on the circuit diagram (and vice-versa)."