Naturally the Silver-Reed calculation machine is the most impressive calculator we have but not the one we actually use, that one is the Commodore Business Machines 776M. This is a typical calculator from the mid-1970s (indeed it was probably built in 1974) when mass production and a reduced number of components meant that the cost of pocket calculators was dropping and would stay low.
The 776M has a Commodore GRBP-67 integrated circuit and has the basic four arithmetric functions plus a percentage function and a basic memory function. The display is a seven segment red LED which gives a pleasing retro effect. The calculator is powered by a 9v battery (though can be powered by an external charger if available).
