Memory Organization of 8051 Microcontroller 8051 micro-controller is based on the Harvard architecture, which supports separate program memory and separate data memory. The following paragraph explains the memory supported by 8051. Program Memory 8051 supports 4 KByte internal and 60 KByte external i.e. a total of 64 KByte of program memory. Selection of Program memory 8051 has an external access (EA) for selection of internal or external program memory. When EA=1; internal 4 KByte ROM is first fetched, control automatically transfers to external ROM once internal program memory limit is exceeded. When EA=0; Only the external program memory is accessible. So, the internal program memory is bypassed. Figure 6.1 shows the program memory of 8051   Internal Data Memory 8051 has 256 byte internal data memory of this the

Introduction to Micro-controllers Microprocessors and micro-controllers are widely used in embedded system products. An embedded product uses a microprocessor (or micro-controller) to do one task and one task only. Whereas a micro-controller is used in an embedded system which perform a specific and a dedicated task, a microprocessor is used in systems which can perform multiple tasks wiz a computer. A printer is an example of embedded system since the processor inside it performs only one task; namely, getting the data and printing it. PC on the other hand can be used for any number of applications such as word processor, print server, bank teller terminal, video game player, network server, or internet terminal. PC generally uses an operating system and