HP started designing handhelded calculators from 1968 until the end of ‘80. I buyed an HP-42S around 1993 but it has been designed near 1986.

Here I want to focus on the chip design of the 10C series, a compact set of calculator with programming abilities but with full numeric display. The HP-15C was introduced in 1982, in the full 8bit computer era, the same year of the C/64. Later model will feature a more mature “Saturn” processor. I will describe here this chip at the best of my abilities, because it sheds a light on how custom architecture was done around end of 1979.

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The HP-12C is the only HP RPN calculator which is still produced and sold, despite is was designed in 1980. The calculator is produced by a subsidary licensed by HP, and you can find it around 40$ in US and around 70€ in Europe/UK. There was designed more than 14 diferent revisions by HP.

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Ho scritto parecchi articoli sulle calcolatrici HP Saturn in logica RPN, con un misto di nostalgia e amarezza. Scopro oggi che in realtà c'è ancora una calcolatrice in produzione, grazie a questo articolo di TheRegister che documenta un problema di calcolo dell'interesse composto, che affligge alcuni modelli.

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