- Images of the original 4004 schematics from the Intel archives (PDF).
- An amazing Java program written by Lajos Kintli to analyze the photomicrographs of the 4004 chip and match physical structures to the schematic. It will also then simulate the execution of the 4004 and companion chips (4001, 4002, 4003). The ZIP file includes bitmap images of each layer and the schematics.
- The 4004 35th anniversary project website. Lots of great stuff, including a redrawn version of the schematic with searchable text strings.
- Frederico Faggin's website, explaining his critial involvement in the creation of the 4004, 8008, 8080, and eventually the founding of the Zilog corporation whose Z80 processor is still used today.
- Intel's website on the 4004.
Most of the materials are available under the Creative Commons non-commercial license.
The bits of schematic I've posted are from the redrawn schematic from the 35th Anniversary project, which is derived from Intel's schematic. Please respect the licenses!