Microprocessor and Microcontroller Notes

Microprocessor and Micro controller Notes

 

Microprocessor and Micro controller

The general purpose Microprocessors are Intel’s x86 family, Motorola’s 680×0 family etc. These Microprocessors contain no RAM, no ROM, no I/O ports on the chip itself. So it is called general purpose microprocessors. A system designer using a general purpose microprocessor such as the Pentium or the 680 40 must add RAM, ROM, I/O ports and timers externally to make them functional. The addition of external RAM, ROM and I/O ports makes these system bulkier and much more expensive, they have the advantage of versatility such that the designer can decide on the amount of RAM, ROM, and I/O ports needed to fit the task at hand. A micro controller has a CPU or microprocessor in addition to a fixed amount of RAM, ROM, I/O ports and a timer all on a single chip Inner controller the processor, RAM, ROM, I/O ports, and timer are all embedded together on one chip. Therefore, designer can’t add any external memory I/O or timer of it to a fixed amount of on-chip ROM, RAM & number of I/O ports in micro controller make then ideal for many applications in which cost and space are critical

 

Two 16-bit registers in 8051 and their functions

The two 16-bit registers in 8051 are DPTR and program counter DPTR is Data Pointer The function of program counter is to point to the address of next instruction to be executed. As CPU fetches the opcode from program. ROM, the program counter is incremented to point to the next instruction It is 16-bit wide in 8051 and the function of DPTR is to access, with the external Memory.

 

Embedded system

Embedded system also called dedicated system. An embedded product uses a microprocessor to do one task and one task only. Example is printer, it performs one task only, getting the data and printing it.

 

Criteria for choosing a micro controller

Three criteria in choosing micro controller are :

(a)Meeting the computing needs of task at hand efficiently and cost effectively. (b) Availability of software development tools such as compilers, assembler and debuggers. (c) Wide availability and reliable sources of micro controller.

 

8051 and 8052 micro controller?

The 8052 is another member of 8051 family. The 8052 has all the standard features of 8051 in addition to an extra 128 bytes of RAM and an extra timer 8052 has 256 bytes of RAM and 3 timers. It has also 8k bytes of on chip program ROM instead of 4k bytes. All the programs written for 8051 will run on 8052, but reverse is not true.

 

List the advantages of Micro controller for some applications. Name three features of 8051.

The advantage of micro controller is:1. A micro controller has a CPU in addition to fixed amount of RAM, ROM, I/O ports and a timer all on a single chip. 2. It is widely used in embedded system products. 3. Many micro controllers such as Motorola 6811, Intel’s 8051, Zilog’s Z8 has a unique instruction set and register set. This is the reason, they are not compatible with each other. Three features of 8051 are:(a) 8051 is. an 8-bit Micro controller means CPU can work on only 8-bits of data at a time. (b) It had 128 bytes of RAM, 4k bytes of o n chip ROM, two timers, one serial port and 4 ports are all on a single chip. (c) 8051 has a maximum of 64k bytes of on chip ROM.

 

8051 and 8031 micro controller?

8031 chip is often referred to as a ROM-less 8051 since it has ok bytes of on-chip ROM. To use this chip, you must adcf external ROM to it. This external ROM must contain the program that the 8031 will fetch and execute. The ROM containing the program attached to 8031 can be as large as 64k bytes. In 8051 on chip ROM contains program to be fetched and executed but it is limited to only 4k bytes of code.

 

Members of 8051 family.

8052 and 8031 are the members of 8051 family. 8052 Micro Controller: The 8052 has all the standard features of 8051 in addition to an extra 128 bytes of RAM and an extra timer. 8052 has 256 bytes of RAM and 3 times. It also has 8k bytes of on-chip program ROM instead of 4k bytes.8031 Micro controller : 8031 chip is often referred to as ROM less 8051 since it has ok bytes of on chip ROM. To use this chip you must add external ROM to it. This external ROM must contain program that 8031 will fetch and execute. The ROM containing the program attached to 8031 can be as large as 64k bytes. In the process of adding external ROM to 8031, two ports are lose. That leaves only two ports of 4 ports for I/O operations. To solve this problem, external I/O should be add to 8031.

 

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