Following are the main features of Micro controller 8051 which makes it most efficient Microcontroller chip:

● It Includes Boolean Processing Engine. Thus internal registers and RAM can carry Boolean logic operations directly and efficiently.

● It gives us many functions in a single chip. (For example: CPU, RAM, ROM, I/O Interrupt, Timer etc.)

● It has 8 bit Data bus.

● It has 8 bit Stack Pointer.

● It has 16 bit Program Counter.

● It has 16 bit address bus which can access almost 65,536 memory locations.

● Data memory or RAM of 128 bytes. (On-Chip). The data memory can be expanded up to 64kb.

● Program Memory or ROM of 4 KB. (On Chip).

● It has 4 parallel I/O port: port0, port1, port2, port3. Each port is 8-bit bi-directional I/O port. Each port is bit/byte addressable.

● It has 4 register banks: bank 0, bank 1, bank 2, and bank 3. Each register bank consists of 8 register (R0 to R7).

● Serial Port or UART (This serial communication port makes chip to use simply as a serial communication interface).

● It features Power Saving Mode which saves power.

● Two Timers/Counters each of 16 bit.

● Internal and External Interrupt Sources.

● It has 11 special function register.

● It has 111 instructions, 64 instructions are single cycle.