The 8051 is a Harvard architecture, single chip microcontroller (µC) which was developed by Intel in 1980 for use in embedded systems. The official designation for the 8051 family is MCS 51. Intel’s original versions were popular in the 1980s and early 1990s, but has today[update] largely been superseded by a vast range of faster and/or functionally enhanced 8051-compatible devices manufactured by more than 20 independent manufacturers including Atmel, Infineon Technologies (formerly Siemens AG), Maxim Integrated Products (via its Dallas Semiconductor subsidiary), NXP (formerly Philips Semiconductor), Nuvoton (formerly Winbond), ST Microelectronics, Silicon Laboratories (formerly Cygnal), Texas Instruments and Cypress Semiconductor.
Intel’s original 8051 family was developed using NMOS technology, but later versions, identified by a letter C in their name (e.g., 80C51) used CMOS technology and were less power-hungry than their NMOS predecessors. This made them more suitable for battery-powered devices.
It provides many functions (CPU, RAM, ROM, I/O, interrupt logic, timer, etc.) in a single package
- 8-bit ALU, Accumulator and 8-bit Registers; hence it is an 8-bit microcontroller
- 8-bit data bus – It can access 8 bits of data in one operation
- 16-bit address bus – It can access 216 memory locations – 64 KB (65536 locations) each of RAM and ROM
- On-chip RAM – 128 bytes (data memory)
- On-chip ROM – 4 kByte (program memory)
- Four byte bi-directional input/output port
- UART (serial port)
- Two 16-bit Counter/timers
- Two-level interrupt priority
- Power saving mode (on some derivatives)