This section includes a variety of technical notes, internal descriptions, and reference material that goes beyond the basic information on a machine's make and model.
The notes were written originally for my own use, to assist me in understanding the technology and the operation of the machines in my own collection. They are based primarily on my own observations, often involving reverse-engineering of both hardware and software, and supplemented by published manuals, patent descriptions, and third-party data. The amount and type of detail varies, depending on how keen I was to get to the bottom of things.
The calculators described here range from 30 to more than 100 years old, and may reasonably be considered a part of the historical record. These technical notes are presented in the hope that they will assist others in the understanding and preservation of this important part of our engineering heritage.
While I believe my descriptions to be substantially correct, I do not guarantee that they are accurate, complete, or applicable to any other machine. Please do not disassemble your calculator in the expectation that these notes alone will get it back together!
I would be happy to receive corrections, further information, or enquiries from like-minded enthusiasts.