Analysis of information sources in references of the Wikipedia article "78K" in English language version.
NEC 78K.
The 78K/IV has upward compatibility regarding the instruction sets of the existing 78K/0, 78K/II and 78K/III. Major features of the 78K/IV are: 1) linear addressing of 16 M bytes, 2) wide operative voltage = 2.7-6.0 V, 3) efficient power management, 4) instruction sets for C compiler. NEC has developed the 1st product "puPD784026 subseries" that has upward-compatible peripheral functions of the 78K/II series.