TI SR-50

The SR-50 was Texas Instruments' first scientific pocket calculator with trigonometric and logarithm functions. It enhanced their earlier SR-10 and SR-11 calculators, introduced in 1973, which had featured scientific notation, squares, square root, and reciprocals, but had no trig or log functions, and lacked other features. The SR-50 was introduced in 1974 and sold for US$170. It competed with the Hewlett-Packard HP-35.