Books

Understanding Digital Computers - Radio Shack (Forrest Mims)

This was the first book I read that explained the inner workings of a computer and is still one of the best instructions to the subject. The Forrest M. Mims Radio Shack books like this one and the Engineer’s Notebook series must have inspired countless engineers over the years.

Digital Computer Electronics - Paul Malvino

This is the definitive source for the SAP-1 design and its successors. It also includes a wealth of other source material that leads up to the design. This is not written at the same beginner level as the Mims book, but it covers the subject with much more detail.

These are a just a few of the other breadboard computers and interesting sites I’ve run across while building this project. There is a large community willing to learn and share what they know with others.

Ben Eater 8-bit computer (SAP-1) is the starting point for these projects. This video series builds a simple computer from the ground up and explains all of the design aspects along the way. Don’t bother with any other sites before checking this one out. The website also has complete kits of parts available to build a SAP-1.

On the r/beneater reddit, there is a “What I Have Learned” post by lordmonoxide. This is full of useful debug tips, including the solution to a noise problem on the HALT line that was causing my clock circuit to double count.

Troy Schrapel’s vrcpu is a breadboard computer that is supported by a wireless program loader, an assembler, and a web-based graphical emulator.

The Rolf Electronics 8-bit SAP-3 is a very nicely constructed and well-documented extension to the SAP-1.

The Homebrew Computer Club group on facebook has a lot of posts featuring 8-bit breadboard computers and other interesting projects.

A deep dive into the 74LS181 ALU can be found on Ken Shirriff’s blog, including a detailed walk-through of the operations. For a detailed history of the 74181, see the Apollo181 by Gianluca G. project.

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