A newsbrief announcing Japan's Nippon Electric Co. (NEC) developing a single integrated circuit that contains a 4-bit latch, a Binary Coded Decimal(BCD) to 1 of 10 decoder, both implemented with MOS transistors; as well as bipolar driver transistors for directly driving the digit anodes (zero through nine and the decimal point) in a traditional Nixie-style gas-discharge display tube. The unique aspect of this IC is that it combines both MOS and bipolar transistors on the same chip, involving some unique IC fabrication processes that NEC's engineers had developed. MOS (Metal Oxide Semiconductor) and bipolar transistors are rather different beasts, with MOS transistors being very simple to fabricate and very tiny, but can't handle much voltage, while bipolar transistors are significantly more complex to fabricate, and consume quite a bit more real-estate on the chip, but can handle higher voltages and current. The challenge came in combining these two types of transistors on a single chip.

In the case of the chip outlined in the article, the MOS transistors are used where their simplicity in fabrication and tiny size provide the most bang for the buck, in the storage and decoding logic. However, the MOS transistors would fry instantly at the voltages required by Nixie tubes. In order to be able to directly drive the anodes (the wires inside the tube that are formed in the shape of the digits) of the Nixie tube, bipolar transistors were needed. Bipolar transistors created on a chip are still hundreds of time smaller than discrete bipolar transistors, even the smallest discrete transistors made at the time. By combining both types of transistor on the same chip, NEC was able to reduce the number of discrete transistors used in the display driver circuitry for a calculator. This saved space and complexity on the circuit board as well as reducing component cost; both which were major factors for success in the highly competitive electronic calculator market of the late 1960's and early '70's.

The device described in the newsbrief became the NEC µPD116, which was used in the display section of quite a number of electronic calculators beginning in 1969 through the early 1970's, including the Casio 121-A/AS-A and the Casio AS-L.

One may note that there are still some discrete transistors or hybrid devices that are used in the display section of calculators using this chip. These additional external transistors are used to switch the cathodes of the Nixie tubes(the fine wire grid positioned in front of the digit-shaped anodes), which are scanned in a sequential fashion called multiplexing. Multiplexing allows a single decoder/driver chip (e.g., the µPD116) to be shared by as many Nixie tubes as there are digits in the display system.