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The CD400 uses 12 nixie tubes for its display.  The nixie tubes are driven by discrete transistors.  

Logic operations are taken care of by DTL integrated circuits.  This kind of  circuits were produced from the early 60s onward by several manufacturers, Philco being one of them.  A Matsushita JM-227 delay line module is used for its memory.

Proving the reliability of these early integrated circuits no repair was needed, a major difference with the Canon 130s built with discrete transistors and diodes.

Delay-line memory

(Source: Wikipedia)

DTL-based logic