Texas Instruments

Model: SR-40 LCD Battery: 2 x AA Adapter: NO Year: 1981Chip: TP0320 Manual: Info: The extremely rare SR-40 LCD (1981) calculator produced in Brazil is an interesting model, as at first glance it looks very similar to the European version of the TI-30 LCD. However, a few differences set it apart. One of the most noticeable differences concerns the keys: while the European TI-30 LCD features the **N!** (factorial) key, the Brazilian SR-40 LCD has the **x!** key, a detail that might reflect slight variations in functionality or target use. Another notable difference is the design of the battery compartment. The SR-40 LCD uses two AA batteries, but the compartment cover requires a coin to be opened, unlike the sliding cover of the European TI-30 LCD. This feature probably represents an adaptation for greater durability or security in battery replacement. These small variations between the models highlight production differences between different markets, making the SR-40 LCD a particularly rare and interesting piece for vintage calculator collectors.

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Classic 1 generation

Model: SR-50 Battery: BP 1 Adapter: AC9200 Year: 1974Chip: TMC0501 / 0521 Manual: with permission www.datamath.org Info: TIP line - classic first GENERATION

Model: SR-50 Dismac Battery: BP 1 Adapter: AC9200 Year: 1974Chip: TMC0501 / 0521 Manual: Info: Fellow calculator collector Marie Lisa Collas surprised us in December 2015 with this unusual looking SR-50manufactured for Dismac Industrial S.A. in Brazil. Texas Instruments changed the appearance of the original dramatically by simply switching the silver colored aluminum bezel from the display frame to the keyboard. Purchased in 2022.

Classic 1 generation

Model: SR-51 1vDisplay: 10 + 2 Battery: BP 1 Adapter: AC9200 Year: 1975Chip: TMC0501, TMS0522, TMC0523 Manual: Info: With the SR-51 Texas Instruments began a series of scientific calculators that added statistical functions and conversions to the "usual functions". But none of them are engineered as flawlessly as the SR-51. It was built as a tank to survive decades of use like its close relative SR-50. Compared to previous models, the SR-51 got a keyboard design with white, gray, yellow and orange keys and gave a perspective to later TI calculators. To reduce manufacturing costs and to give a similar look and feel to the SR-52 and SR-56 calculators, the SR-51 was replaced within months with the SR-51A. Logically it is quite rare. However, two different variants are known: this model from an early production batch uses huge yellow characters for the 2 shifted functions, while the later SR-51 sports much finer print.

This rare model had many parts corroded by battery acid, the 7-segment displays completely corroded, the replacement and cleaning of the keyboard can be seen on the side.