The Intel 8051 is a Harvard architecture single chip microcontroller (µC) which was developed by Intel in 1980 for use in embedded systems.It has spawned countless derivatives maintaining various levels of compatibility with the original. Several 80C51 (C originally added when the design was ported to CMOS) core versions have been developed using various clocking schemes to speed up the execution of instructions and improve instructions per megahertz and/or power consumption per operation.
From an early Intel description of the MCS 51 device:
The 8051 is the original member of the MCS(R) 51 family, and is the core for all MCS 51 devices.
The features of the 8051 core are:
- 8-bit CPU optimized for control applications
- Extensive Boolean processing (Single-bit logic) capabtilties
- 64K Program Memory address space
- 64K Data Memory address space
- 4K bytes of on-chip Program Memory
- 128 bytes of on-chip Data RAM
- 32 bidirectional and individually addressable 1/0 lines
- Two 16-bit timer/counters
- Full duplex UART
- 6-source/5-vector interrupt structure with two priority levels
- On-chip clock oscillator