78K

78K is the trademark name of 16- and 8-bit microcontroller family^{[1]: 23-4–23-5 [2]: 78} manufactured by Renesas Electronics, originally developed by NEC^{[3][4]: 229} started in 1986.^{[5]: 7, line 2} The basis of 78K Family is an accumulator-based register-bank CISC architecture. 78K is a single-chip microcontroller, which usually integrates; program ROM, data RAM, serial interfaces, timers, I/O ports, an A/D converter, an interrupt controller, and a CPU core, on one die.^{[6][7]: 412}

78K Family microcontrollers

General information
Launched	1986; 39 years ago (1986)
Discontinued	current
Common manufacturer	Renesas Electronics (formerly NEC)
Performance
Max. CPU clock rate	32 kHz to 24 MHz
Data width	16/8
Address width	20(24)/16
Architecture and classification
Application	Embedded
Instruction set	78K Family
Physical specifications
Cores	1
Products, models, variants
Variant	78K0R, 78K0S, 78K0, 78K4, 78K6, 78K3, 78K7, 78K1, 78K2
History
Predecessors	87AD Family, 17K Family
Successor	RL78 Family

78K0/KX1+ board with in-circuit emulator; MINICUBE

78K0S/KA1+ Do It board

78K0R/KG3 Cool It board with in-circuit emulator; IECUBE ^{(formerly, MINICUBE2)}

Its application area is mainly simple mechanical system controls and man-machine interfaces.^[8][9][10]

Regarding software development tools, C compilers and macro-assemblers are available.^[11]: 99 As for development tool hardware, full probing-pod type and debug port type in-circuit emulators,^[12][13] and flash ROM programmers^{[14]: 22–24} are available.

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]

Variants

78K0 Series

78K0 Series [de; jp] (also known as 78K/0) is a long-running 8-bit single chip microcontroller,^[18] which is the basis of 78K0S [jp] and 78K0R Series. It contains 8× 8-bit registers ×4 banks. For 16-bit calculating instructions, it performs ALU operation twice. Each instructions are performed serially without instruction pipelining. It has 16-bit 64K Byte address space.^[19] Some variants of 78K0 have affordable and compact type 8-bit R-2R D/A converter, which does not have monotonicity because it is not trimmed for adjustment nor followed by operational amplifier.

In its earlier stage, the Program Memory was one-time PROM (OTP), UV-EPROM, or mask ROM.^[20] But with the times, it became flash memory.^[21][22]

78K0S Series

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 as multiplication and division, are removed from 78K0 instruction set architecture.^[26]

78K0R Series

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 Quantum Fireball 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.

78K1 Series

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 for servo controls of videocassette recorders. μPD78148 sub-series integrates 2 operational amplifiers.^[40]

78K3 Series

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}

This series is used for hard disk drives, especially Quantum Fireball Series.^[42] μPD78364 sub-series is used for inverter compressor controls.^[43] It is also used for traction control systems of some cars.

78K2 Series

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]

17K Family

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

Table list of 78K Family

Series	ALU	Registers	Instructions	Pipeline	Remark	Documents
RL78-S3	16-bit	8× 8-bit ×4 banks	81 (75+6)	3-stage	Successor of 78K0R	[29]: 8
RL78-S2	16-bit	8× 8-bit ×4 banks	75	3-stage
RL78-S1	8-bit	8× 8-bit (no bank)	74 (75-1)	3-stage
78K0R	16-bit	8× 8-bit ×4 banks	80 (75+5)	3-stage	Extended 78K/0	[28]: 18
78K0S	8-bit	8× 8-bit (no bank)	47	none	Simplified 78K/0	[25]
78K0	8-bit	8× 8-bit ×4 banks	48	none	Basic 78K/0 core	[19]
178K0S	8-bit	8× 8-bit	47	none	78K/0S for DTS; Digital Tuning System	[25][32]
178K0	8-bit	8× 8-bit ×4 banks	48	none	78K/0 for DTS	[19][31]
78K4	16-bit	16× 8-bit ×4 banks	113	none	Macro service available	[37]: 24, 128
78K7	32-bit	16× 16-bit ×16 banks		none	Macro service available	[46]
78K6	16-bit				Macro service available
78K1	8-bit	8× 8-bit ×4 banks	64	none	For VCR servo controls	[40]: 3, 39
78K3	16-bit	16× 8-bit ×8 banks	113–115	none	Macro service available	[47]: 3–28, 45
78K2	8-bit	8× 8-bit ×4 banks	65	none	General purpose	[44]: 16, 50
87AD	8-bit	8× 8-bit ×2 banks	CMOS: 159 NMOS: 158	none	Predecessor of 78K	[45]: 21, 39
(17K)	4-bit	128× 4-bit ×2 banks	47	none	Predecessor of 178K	[30]

See also

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