This calculator provided functionality that was revolutionary for a pocket calculator at that time. Nowadays, many say a pocket calculator is faster. The question is, is the human mind like the pocket calculator, essentially composed of information? The short-lived TI-10 Profit Guide had similar functions in a pocket calculator size. The flip side featured the Japanese version of "Pocket Calculator," "Dentaku". Traveling Sidekick included a 3-ring binder notebook with solar-powered pocket calculator, and Sidekick software. The FX-501P was used on the 1981 song "Pocket Calculator" by electronic music group Kraftwerk. During World War II, he designed plans for a mechanical pocket calculator (the "Curta"). The HP-15C is a high-end scientific pocket calculator with a root-solver and numerical integration. Meanwhile, Hewlett-Packard (HP) had been developing a pocket calculator. The SR-50 was Texas Instruments' first scientific pocket calculator with trigonometric and logarithm functions. The last pocket calculator supporting RPL, the HP 50g, was discontinued in 2015. One clock-radio model, the TRR81, sported a built-in pocket calculator. The HP-22 was a finance-oriented pocket calculator produced by Hewlett-Packard between 1975 and 1978.