Casio 001

The Casio 001 offered ten-digit capacity, with Nixie tube display, and a ten-key keyboard. It was built upon discrete transistor circuitry, housed on muliple plug-in circuit boards. The knobs across the front of the machine could be set to provide a constant number which could be recalled for repetitive use -- a primitive form of the constant function provided in later calculators. This feature carried over from Casio's earlier relay-based calculators.