Introduction to Microprocessors

Manijeh Keshtgary

Fall 2006

Shiraz University of Technology

What is Computer

Data Processing

Data Storage

Major Components of a Computer

I/O MEMORY

CPU

SYSTEM BUS

What is CPU

CPU

What is CPU?

Control Unit & Instruction Decoder

Arithmetic/Logic Unit

Registers

The Central Processing Unit (or P)

Speed of CPU based on

• It’s Clock

• Format of an instruction

• Parallel nature of instruction execution

• Access time to its memory & I/O

Memory

• Two different types of information stored in memory– Instruction– Data

Example: Adding 2 numbers, addition operation is an instruction and the actual numbers are data

I/O

• Input Device : transfers outside information into computer

Ex: keyboard, mouse, scanner, camera….

• Output device: allows computers to inform their internal states & data to the outside world.

Ex: Monitor, speakers, printers……

Buses

• Think of them as roads that connect different parts of a computer

• 3 types of Buses– Address Bus– Data Bus– Control Bus

Address Bus

• Carry the CPU generated address out to memory & I/O devices

• It is unidirectional and only travel outward from CPU

• No. of address lines that a microprocessor has determines the size of the memory space that it can access

Memory size

No of Add. lines Size of memory space

8 28 = 256

16 216 = 65 536 = 64 K

20 220 = 1 048 576 = 1 M

24 224 = 16 777 216 = 16 M

32 232 = 4 294 967 296 = 4 G

Data Bus

• These are the data signals that travel out of and into the P (bi-directional).

• The number of wires in the data bus depends on the word size that the P operates with.

• An 8-bit P will have a data bus consisting of 8 wires and a 32-bit P will have a data bus with 32 wires.

Control Bus

• The control bus consists of wires, some of which carry signals from the CPU to external devices, while others carry signals from external devices to the CPU.

• The number of wires present in the control bus varies from one P to another.

• Examples of control bus signals are READ, WAIT.

Cache• Faster but smaller memory type.• Small so reduce the memory access latency• Ex: A library with a person behind the desk (LE) (he is

responsible to give you the book you want). • you will read the book it the library and return it.• Customer A ask for book A. LE gets the book from store

room, returns to counter and give it to him.customer A will return the book in few minutes. So LE goes to storeroom,….

• Customer B comes and ask for book A• LE goes to storeroom…….• Is there a way to improve the performance????

Cache

• Yes, we can give LE a backpack to store the last 10 books that customers return

• The backpack is a cache for this system!

• If the data is not is cache (cache miss), are we wasting time???

• We can have 2 level cache.

• Main memory is much larger than cache

Microprocessor, Microcomputer and microcontroller

P : CPU unit packaged in a single chip. Ex: Intel Pentium family

• Microcomputer : A computer that uses P as its CPU. Ex: PC

C created by packaging CPU, Memory and I/O parts and buses in a single VLSI chip.

Two classes of Computers• General Purpose Computer System (GPCS):

Example: Desktop and Laptop

In this type of computer many different software can be installed and run to do many different jobs. Example, MSWord software does the word-processing job

• Application Specific Computer (ASC) Also called Embedded System)

Example: Computer used in mobile telephone, video camera and many other intelligent electronic devices

In this type of computer a specific software runs all the time and does a single specific job. An ASC is very small in size (typically, just a small PCB and few ICs). C is the main IC in embedded system

What is Microcontroller

Embedded system

Microcontroller

General Structure of C

Microcontroller advantages

• I/O interfacing issue is greatly simplified.

• External memory is no longer needed for many applications.

• System design time is greatly shortened.