Features 
There are some key features of 8051 that work as a foundation for students to learn microcontrollers. These features include:

• 4 KB on-chip ROM (Program memory).
• 128 bytes on-chip RAM (Data memory).
• The 8-bit data bus (bidirectional).
• 16-bit address bus (unidirectional).
• Two 16-bit timers.
• Instruction cycle of 1 microsecond with 12 MHz crystal.
• Four 8-bit ports.
• 128 user-defined flags.
• Four register banks of 8 bit each.
• 16-byte bit-addressable RAM.