78K is thetrademark name of 16- and 8-bitmicrocontroller family^{[1]: 23-4–23-5 [2]: 78}manufactured byRenesas Electronics, originally developed byNEC^{[3][4]: 229}started in 1986.^{[5]: 7, line 2}The basis of 78K Family is anaccumulator-basedregister-bankCISCarchitecture.78K is a single-chip microcontroller, which usually integrates;programROM,dataRAM,serial interfaces,timers,I/O ports, anA/D converter, aninterrupt controller, and aCPU core, on onedie.^{[6][7]: 412}

Its application area is mainly simplemechanical system controls andman-machine interfaces.^[8][9][10]

Regardingsoftware development tools,Ccompilers andmacro-assemblers are available.^[11]: 99As for development tool hardware, fullprobing-pod type anddebug port typein-circuit emulators,^[12][13]andflash ROMprogrammers^{[14]: 22–24}are available.

Historically, the family has 11 series with 9instruction 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 toRL78 Family,^[15]which is a successor of 78K0R and almostbinary level compatible with 78K0R,^[16]: 20is recommended.^[17]

78K0 Series [de;jp] (also known as 78K/0) is a long-running 8-bitsingle chip microcontroller,^[18]which is the basis of78K0S [jp] and 78K0R Series. It contains 8× 8-bit registers ×4banks. For 16-bit calculating instructions, it performsALU operation twice. Each instructions are performed serially withoutinstruction pipelining. It has 16-bit 64K Byteaddress space.^[19] Some variants of 78K0 have affordable and compact type 8-bitR-2RD/A converter, which does not havemonotonicity because it is not trimmed for adjustment nor followed byoperational amplifier.

In its earlier stage, theProgram Memory wasone-time PROM (OTP),UV-EPROM, ormask ROM.^[20]But with the times, it becameflash memory.^[21][22]

78K0S Series (also known as 78K/0S) is a low-end version of 78K0.^[23][24][25]It has 8× 8-bit registers, but without any banks. In addition, some instructions, such asmultiplication anddivision, are removed from 78K0instruction set architecture.^[26]

78K0R Series is a 16-bit single-chip microcontroller with 3-stageinstruction pipelining.^[27]Its instruction set is similar to 78K0 and covers 16- and 8-bit operations. It has 20-bit 1M Byteaddress space.^[28] 75 instructions out of 80 are identical with that ofRL78 Family; its successor.^{[16]: 20 [15][29]}

178K0 Series (also known as 178K/0) is a successor of NEC's 17K Family 4-bit microcontroller forDTS (Digital Tuning Systems) andremote controls.^[30]It integrates 17K family's peripheral functions with the 78K0 8-bitCPU core on a chip.^[31]

178K0S Series (also known as 178K/0S) is also a successor of 17K Family with the 78K0S CPU core.^[32]

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 foraddressing modes.^[37] It has 24-bit 16M Byteaddress space. It hasmicrocode-based operations namedMacro Service withinterrupt functions.^{[38]: §23.8, 560–593}

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 hasmicrocode-based operations namedMacro Service withinterrupt functions. It has 24-bit 16M Byte linear address space. It is used for someQuantumFireball products,^{[39]: Photo 2}but shortly replaced withV850 Family 32-bitRISC microcontrollers.

78K6 Series (also known as 78K/6) is a 16-bit single-chip microcontroller. Its life-time was short, and less variants.

78K1 Series (also known as 78K/1) is an 8-bit single-chip microcontroller. It has 8× 8-bit registers ×4 banks. 78K1 series is targeted forservo controls ofvideocassette recorders. μPD78148 sub-series integrates 2operational amplifiers.^[40]

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 hasmicrocode-based operations namedMacro Service withinterrupt functions.^{[41]: §13.4, 261–280}

This series is used forhard disk drives, especiallyQuantumFireball Series.^[42]μPD78364 sub-series is used forinverter compressor controls.^[43]It is also used fortraction control systems of some cars.

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]

87AD Family^[4]: 229 is an 8-bit single-chip microcontroller. It has 8× 8-bit registers ×4 banks. Itsinstruction set architecture became the basis of 78K.^[45]

17K Family^[4]: 229 is a 4-bit single-chip microcontroller, especially dedicated forDTS (Digital Tuning Systems) andremote controls. It has 2 plane of 128× 4-bitregister files, and sophisticated fullyorthogonal instruction set. This instruction set is completely different from that of 78K Family.^[30]

• RL78
• NEC V20
• V850
• Renesas 740
• IEBus

• Technical documents
  • Application note: 78K/0 Series Basic (I) | Renesas Electronics
  • Application note: 78K/0 Series Basics(II) | Renesas Electronics
  • Application note: 78K/0 Series Basic (III) | Renesas Electronics
• Web sites
  • 78K Family | Renesas Electronics
  • 78K Family Software & Tools | Renesas Electronics
  • CPU of the Day: NEC 78C11 Sample and the 78K family | The CPU Shack MUseum
  • TESSERA TECHNOLOGY, Inc.

• NEC microprocessors
• Renesas microcontrollers

• CS1 Japanese-language sources (ja)
• CS1 German-language sources (de)
• CS1 Russian-language sources (ru)
• Articles with short description
• Short description matches Wikidata