Microprocessors-Introduction to Computing-Lecture Slides, Slides of Microprocessor and Interfacing

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CS101 Introduction to Computing

Lecture 7

Microprocessors

The last lecture, Lec 6, was on Web dev.

Today‟s lecture, however, is a follow-up to Lec 5

• In lecture 5, we looked at the components that we bring together to form a PC
• We looked at ports, power supply, mother board, add- on cards (modem, LAN, video), memory, hard disk, floppy disk, CD, and the microprocessor and the associated cooling apparatus
• Today our focus will be on one of those components, the microprocessor

Microprocessor

• The key element of all computers, providing the mathematical and decision making ability
• Current state-of-the-art uPs (Pentium, Athlon, SPARC, PowerPC) contain complex circuits consisting of tens of millions of transistors
• They operate at ultra-fast speeds – doing over a billion operations very second
• Made up from a semiconductor, Silicon

Integrated Circuits

• Commonly known as an IC or a chip
• A tiny piece of Silicon that has several

electronic parts on it

• Most of the size of an IC comes form the pins

and packaging; the actual Silicon occupies a very small piece of the volume

• The smallest components on an IC are much

smaller than the thickness of a human hair

A microprocessor system?

• uPs are powerful pieces of hardware, but not

much useful on their own

• Just as the human brain needs hands, feet,

eyes, ears, mouth to be useful; so does the uP

• A uP system is uP plus all the components it

requires to do a certain task

• A microcomputer is 1 example of a uP system

Micro-controllers?

• Micro-controllers are another type of uP systems
• They are generally not that powerful, cost a few dollars a piece, and are found embedded in video games, VCRs, microwave ovens, printers, autos, etc.
• They are a complete computer on a chip containing direct input and output capability and memory along with the uP on a single chip. Many times they contain other specialized application-specific components as well docsity.com

More than 90% of the microprocessors/micro-

controllers manufactured are used in

embedded computing applications

In 2000 alone, 365 million uPs and 6.4 billion

micro-controllers were manufactured

The Main Memory Bottleneck

• Modern super-fast uPs can process a huge amount of data in a short duration
• They require quick access to data to maximize their performance
• If they don‟t receive the data that they require, they literally stop and wait – this results in reduced performance and wasted power
• Current uPs can process an instruction in about a ns. Time required for fetching data from main memory (RAM) is of the order of 100 ns

On-Chip Cache Memory (1)

• That small amount of memory located on the

same chip as the uP is called On-Chip Cache Memory

• The uP stores a copy of frequently used data

and instructions in its cache memory

• When the uP desires to look at a piece of data,

it checks in the cache first. If it is not there, only then the uP asks for the same from the main memory

On-Chip Cache Memory (2)

• The small size and proximity to the uP makes

access times short, resulting in a boost in performance (it is easy to find things in a small box placed next to you)

• uPs predict what data will be required for future

calculations and pre-fetches that data and places it in the cache so that it is available immediately when the need arises

• The speed-advantage of cache memory is

greatly dependent on the algorithm used for deciding about what to put in cache or not

Registers

Registers

Microprocessor

Instruction Cache

Arithmetic & Logic Unit

Control Bus Unit Interface Unit

Data Cache

Instruction Decoder

I/O

RAM

Memory Bus

System Bus Floating Point Unit

Bus Interface Unit

• Receives instructions & data from main memory
• Instructions are then sent to the instruction cache, data to the data cache
• Also receives the processed data and sends it to the main memory

Arithmetic & Logic Unit (ALU)

• Also known as the “Integer Unit”
• It performs whole-number math calculations (subtract, multiply, divide, etc) comparisons (is greater than, is smaller than, etc.) and logical operations (NOT, OR, AND, etc)
• The new breed of popular uPs have not one but two almost identical ALU‟s that can do calculations simultaneously, doubling the capability

Floating-Point Unit (FPU)

• Also known as the “Numeric Unit”
• It performs calculations that involve numbers represented in the scientific notation (also known as floating-point numbers).
• This notation can represent extremely small and extremely large numbers in a compact form
• Floating-point calculations are required for doing graphics, engineering and scientific work
• The ALU can do these calculations as well, but will do them very slowly docsity.com