Home Made First Generation Calculators


The development of electronic logic was no doubt of great interest to the electronics enthusiast community. Early generation calculators remained very expensive by the standards of individuals so it must not have been long before enthusiasts began to consider building their own.

First generation machines, requiring many hundreds of transistors, thousands of diodes and complex memories such as magnetic core were most likely out of the reach of home builders and the author is unaware of any such machines by private enthusiasts.

By the 1970s SSI ICs had become reasonably cheap but commercial calculator prices had not yet fallen to low levels. This created an opportunity for enthusiasts to design and build their own machines using 1960s second-generation architectures and 1970s SSI ICs. These designs were published in the electronics magazines of the day and are interesting because they contain full explanations of the architecture and implementation of each design.

Home Made Calculator Catalog


"Digi-Cal" from Practical Electronics (UK) 1972
Digi-Cal4-functions with memory and constant, TTL ICs