Notes: "In the early days of electronic calculators, when only 4-function models were available, or affordable, it seemed to Faber Castell like a good idea to combine the capabilities of a slide rule and a calculator into a single product. This would give you addition and subtraction, which the slide rule never had, as well as quicker multiplication and division. The slide rule in turn would be able to calculate square roots, cubes and cube roots, trig and log-log functions. In April 1973 the Faber Castell TR-1 was born. The TR-1 had an 8-digit, red LED display, and was powered by four very large button-cell batteries, the model 150 DK rechargeable nickel-cadmium battery made by DEAC (Deutsche Edison-Akkumulatoren-Company). Faber Castell sold a charger for them. Production of the TR-1 only lasted two years, and Faber Castell’s foray into electronic calculators ended entirely in 1977. The serial number of this one indicates it was made in July 1974. For more information on the Faber Castell TR-1 (and TR-1N, -2, -3, -4, and TRX) see Dieter von Jezierski’s article in the Fall 2001 issue of the Journal of the Oughtred Society."
