• 8-bit Microcontroller –

The 8051 Microcontroller is an 8-bit Microcontroller. what does this imply? This signifies that the width of the data bus is 8-bits. The data bus is utilized to carry data from specific operations. Consequently, the CPU can process 8 bits of data at one time.

  • Memory –

A Microcontroller needs program memory to store program/instructions to perform defined tasks. This memory is termed as ROM. Furthermore the Microcontroller also requires data memory to store the operands/data on a temporary basis. This memory is known as RAM. The 8051 Microcontroller is built with 4 Kb on-chip Read Only Memory (ROM) and 128 bytes Random Access Memory (RAM).

  • Address Bus –

A bus of the Microcontroller can be defined as a group of wire which can act as a medium for the transfer of data. There are two buses present in the 8051 Microcontroller. While we are already aware of the Data Bus, let us know about the Address Bus of the 8051 Microcontroller. The address bus, which is used to address memory locations, is 16-bit wide. Furthermore, the address bus can also be used to transfer data from the CPU (Central Processing Unit) to the memory. Hence, for obvious reasons the address bus is unidirectional.

  • Interrupts –

The most powerful attribute of the 8051 Microcontroller is the concept of Interrupts. The interrupt is a mechanism to –
  • Temporarily suspend the ongoing program,
  • Pass the control to a subroutine,
  • Execute the subroutine,
  • Resume the ongoing/main program.
Interrupts can be of various types, such as, Software and Hardware interrupts, Non-maskable and maskable interrupts, etc. Now the 8051 Microcontroller incorporates five interrupts. These are :
  1. INT0 – External Hardware Interrupt.
  2. TF0 – Timer 0 Overflow Interrupt.
  3. INT1 – External Hardware Interrupt.
  4. TF1 – Timer 1 Overflow Interrupt.
  5. R1/T1 – Serial communication Interrupt.

  • Input/Output Ports –

The 8051 Microcontroller needs to be connected to the peripheral devices in order to control their operations. The I/O Ports are responsible for the connection of the Microcontroller to its peripheral devices. There are total Four 8-bit Input/Output Ports present in this Microcontroller.

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