Historically, the family has 11 series with 9 instruction set architectures. As of 2018, 3 instruction set architectures, those are 8-bit 78K0, 8-bit 78K0S, and 16-/8-bit 78K0R, are still promoted for customers' new designs.[14]
But in most of cases, migration to RL78 Family,[15]
which is a successor of 78K0R and almost binary level compatible with 78K0R,[16]: 20
is recommended.[17]
78K0R Series is a 16-bit single-chip microcontroller with 3-stage instruction pipelining.[27]
Its instruction set is similar to 78K0 and covers 16- and 8-bit operations. It has 20-bit 1M Byte address space.[28] 75 instructions out of 80 are identical with that of RL78 Family; its successor.[16]: 20 [15][29]
178K0 Series
178K0 Series (also known as 178K/0) is a successor of NEC's 17K Family 4-bit microcontroller for DTS (Digital Tuning Systems) and remote controls.[30]
It integrates 17K family's peripheral functions with the 78K0 8-bit CPU core on a chip.[31]
178K0S Series
178K0S Series (also known as 178K/0S) is also a successor of 17K Family with the 78K0S CPU core.[32]
78K4 Series
78K4 Series (also known as 78K/4) is a 16-bit single-chip microcontroller with 16 and 8-bit operations.[33][34][35][36]
It has 16× 8-bit registers ×4 banks, which can be also used for 8× 16-bit registers ×4 banks. Some of these registers can be also used as 24-bit extension for addressing modes.[37] It has 24-bit 16M Byte address space. It has microcode-based operations named Macro Service with interrupt functions.[38]: §23.8, 560–593
78K7 Series
78K7 Series (also known as 78K/7) is a 32-bit single-chip microcontroller with 32, 16 and 8 bit operations. It has 8× 32-bit registers ×16 banks, which can be also used for 16× 16-bit registers ×16 banks and 16× 8-bit registers ×16 banks. It has microcode-based operations named Macro Service with interrupt functions. It has 24-bit 16M Byte linear address space. It is used for some QuantumFireball products,[39]: Photo 2
but shortly replaced with V850 Family 32-bit RISC microcontrollers.
78K6 Series
78K6 Series (also known as 78K/6) is a 16-bit single-chip microcontroller. Its life-time was short, and less variants.
78K3 Series (also known as 78K/3) is a 16-bit single-chip microcontroller with 16 and 8 bit operations. It has 16× 8-bit ×8 banks, which can be also used for 8× 16-bit registers ×8 banks. Its address space is 16-bit 64K Byte. It is developed as high-end series of 78K Family. It has microcode-based operations named Macro Service with interrupt functions.[41]: §13.4, 261–280
78K2 Series (also known as 78K/2) is an 8-bit single-chip microcontroller. It has 8× 8-bit registers ×4 banks. It is developed as general purpose series of 78K Family.[44]
Predecessors
87AD Family
87AD Family[4]: 229 is an 8-bit single-chip microcontroller. It has 8× 8-bit registers ×4 banks. Its instruction set architecture became the basis of 78K.[45]
^ abcParai, Manas Kumar; Das, Banasree; Das, Gautam (January 2013). "An Overview of Microcontroller Unit: From Proper Selection to Specific Application". International Journal of Soft Computing and Engineering (IJSCE). 2 (6): 228–231. ISSN2231-2307. S2CID11529467.
^NECエレクトロニクス 8ビットマイコンのあゆみ [History of 8-bit microcontrollers of NEC Electronics] (PDF) (in Japanese). Sunhayato Corp.
^
Kim, Dahoo; Hida, Itaru; Fukuda, Eric S.; Asai, Tetsuya; Motomura, Masato (November 2014). A Study of Transparent On-chip Instruction Cache for NV Microcontrollers. The Seventh International Conference on Advances in Circuits, Electronics and Micro-electronics. pp. 26–29. CiteSeerX10.1.1.676.6935. ISBN978-1-61208-379-7. ISSN2308-426X.
^JPRS Report: Science & technology. Japan. Foreign Broadcast Information Service. 1994. p. 25. 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.