Multiply, divide and compare instructions.

Boolean processor with 17 instructions, 1-bit accumulator, 32 registers (4 bit-addressable 8-bit) and up to 144 special 1 bit-addressable RAM variables (18 bit-addressable 8-bit).

8- bit arithmetic logic unit (ALU) and accumulator, 8-bit registers (one 16-bit register with special move instructions), 8-bit data bus and 2×16-bit address buses, program counter, data pointer, and related 8/11/16-bit operations hence it is mainly an 8-bit microcontroller.

The 8051 architecture provides many functions ( central processing unit (CPU), random-access memory (RAM), read-only memory (ROM), input/output (I/O) ports, serial port, interrupt control, timers) in one package: Beyond these physical devices, several companies also offer MCS-51 derivatives as IP cores for use in field-programmable gate array (FPGA) or application-specific integrated circuit (ASIC) designs.

Some derivatives integrate a digital signal processor (DSP). While Intel no longer manufactures the MCS-51, MCS-151 and MCS-251 family, enhanced binary compatible derivatives made by numerous vendors remain popular today. The family was continued in 1996 with the enhanced 8-bit MCS-151 and the 8/ 16/ 32-bit MCS-251 family of binary compatible microcontrollers. This made them more suitable for battery-powered devices. Intel's original MCS-51 family was developed using N-type metal-oxide-semiconductor ( NMOS) technology like its predecessor Intel MCS-48, but later versions, identified by a letter C in their name (e.g., 80C51) use complementary metal–oxide–semiconductor ( CMOS) technology and consume less power than their NMOS predecessors.

It is an example of a complex instruction set computer (but also possessing some of the features of RISC architectures, such as a large register set and register windows), and has separate memory spaces for program instructions and data. Intel's original versions were popular in the 1980s and early 1990s and enhanced binary compatible derivatives remain popular today. The architect of the Intel MCS-51 instruction set was John H. The Intel MCS-51 (commonly termed 8051) is a single chip microcontroller (MCU) series developed by Intel in 1980 for use in embedded systems.

Microcontroller 8051 datasheet