8051 Internal Architecture 8051 microcontroller was developed by Intel in 1980s. It is an 8-bit controller and is based on Harvard Architecture which uses two separate memory for storing program and data. The internal architecture describes the organization of the internal components of 8051. Figure 5.1 shows the internal architecture of 8051. Internal components of 8051 Internal Memory: 8051 has two separate memory blocks these are program memory (ROM) and data memory (RAM). Data Memory RAM is used as data memory. 8051 has 256 byte of direct addressable memory and 128 byte indirect addressable memory. 256 Byte RAM includes four register banks named bank 3 through bank 0. Each bank contains 8-register each of 8-bits. they are name R7 through R0. It also include 16