Lecture 3 - Instruction Set - Al Chip Interfaces Chip interface for a microprocessor Microprocessor chip is not stand alone To make it work must add Memory I/O interfaces Timing Other support pin connections that are processor specific Support pins like RESET 9/20/6 Lecture 3 - Instruction Set - Al

Microprocessors and microcontrollers What is the difference in a microprocessor and a microcontroller? Microprocessor – needs memory, I/O, and other support to operate. Microcontroller – almost stand alone Many have internal clock – can add an external crystal if desired but usually not required RAM and ROM on the chip (although limited in size) I/O on chip – often dual use for I/O and address/data to/from memory Minimal external support needed 9/20/6 Lecture 3 - Instruction Set - Al

Microprocessor contains only a CPU Microprocessor contains only a CPU. In contrast Microcontroller contains few other components apart from CPU, which includes RAM, ROM and other peripherals like ports, clock, timer, UART (Universal Asynchronous Receiver Transmitter), ADC (Analog to digital converter), DAC (Digital to analog converter), Drivers for LCD, etc Microprocessor can be considered as just the processor, while microcontroller can be seen as a small computer which is embedded on a single IC (Eg. 8051).

Since microcontroller can be embedded on a single IC, it is used mostly for embedded applications or for a more specific job. On the other hand, microcontroller are used for wider range of applications. For example, In Automotive applications, microcontrollers are used only for some specific tasks; while in computers, microprocessors are used for many applications ranging from ‘basic mathematical computation’ to ‘design and implementation of complex engineering problems’. Since microcontroller has inbuilt memory and peripherals, it is cheaper when compared to microprocessors which becomes costlier on addition of external memory and circuit components. Due to the absence of memory in the microprocessors, it is difficult to perform Boolean operations in them as compared to controllers. For the same reason, number of instructions required to access data from external memory is more in the case of processors compared to the controllers.