8051 has internally Harvard architecture developed by Intel in 1970s for use in embedded systems. It has basic features of microprocessors with internal ROM, RAM, input output ports inbuilt on a single chip. Microcontroller is a device in which entire computer manufactured on a single chip. Microcontroller has 3 basic sizes: Standard, short, extended Sort and extended chips are available in DIP (dual-in-line package), but extended 8051 models have differ form factor, and are not drop in compatible.

History of 8051

In 1981, intel corporation introduced an 8 bit microcontroller called 8051. It has on chip 128 bytes of  RAM, 4k bytes ROM, two timers one serial port and four general purpose input output port. Texas instruments engineers Gary Boone and Michael Cochran introduced first microcontroller in 1971, known as TMS 1000, which was read-only memory, read/write, processor and clock on one chip, partly in response to the existence of single chip TMS 1000, Intel developed a computer system on chip Intel 8048. Most microcontroller at that time had erasable EPROM program memory which can be erased by exposure of UV light. On other hand a PROM varient was introduced which was only programmable once. In 1993 EEPROM was introduced which was easy to erase by electricity , it was electrically erased quickly without any expensive package, allowing both rapid prototyping, and in system programming. Now a days microcontroller are cheap and easily available, in future MRAM could potentially be used in microcontroller as it has infinite endurance.

It can be classified on the basis of bits

8 bit and 16 bit

  • 8 bit means 8 bit data can travel on its data bus.
  • 16 bit means it can process 16 bit on data bus.

Features of 8051 Microcontroller

  • 4kb on chip program memory
  • 128 bytes on chip data memory (RAM )
  • 8 bit data bus
  • 16 bit timer
  • 3 internal and 2 external interrupts
  • 1 micro sec instruction cycle with 12 MHz crystal.

Criteria for selection of microcontroller in embedded system

Meeting the computing need at hand efficiently and cost effectively

  • Speed
  • Packing
  • Power consumption
  • Cost
  • No. of  input and output pins and timers on chip

Applications of Microcontroller 8051

8051 chips are widely use in control system, telecom applications, robotics as well as in automotive industries. They have high concentration of on chip facilities such as serial port, parallel ports , input and output ports , timers, counters, analog to digital converters and are widely use in home and electronic items such as washing machines mobiles etc. They are also used in medical devices like blood pressure and glucose monitor to display data.