TI-54

The TI-54 was a scientific calculator produced by Texas Instruments, primarily marketed towards engineers and science professionals. It was introduced in 1981, and at the time was the only calculator that could deal with complex numbers. It was discontinued in 1983.

The TI-54 touted features such as "built in algebraic functions for both real and complex numbers", "hyperbolic and trig functions for real numbers", and conversion functions such as polar to rectangular, and degrees/minutes/seconds to decimal degrees. It also came with Texas Instruments' Constant Memory feature, which allowed for data storage even after the calculator was turned off.

Unfortunately, this calculator, like some others of the "slanted series", had the so-called ti key disease, which means that pressed keys were either not recognized at all or were recognized as having been pressed several times. Solving arithmetic problems became a game of patience and the correct result was only obtained through pure luck. Texas Instruments later launched a recall campaign due to massive user complaints and exchanged this model for a successor with an improved keyboard free of charge.