applied tics - lesson 1

7/31/2019 Applied tics - Lesson 1

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Computer science Lesson one 19, October, 2009

Introduction to computers

Basic concepts Information: new knowledge about something with the objective of extracting

another derived knowledge

Computer science: automatic treatment of information

Computer engineering: the science that studies the design, operation and

programming of computers focused on the electronics and digital circuits.

Instruction: elemental operation that a computer can perform

Program: set of instructions

Computer: the machine that executes the program

Information computer Processed Information.

(input) (output)

Computer technology: electronics of the computer.

(Transistors: a semiconductor device commonly used to amplify or switch

electronic signals)

Processor: CPU (central processing units) is the brain of the computer. (CPU ex:

Intel core 2, I 7, PowerPC, Sparc, LEON, etc.)

Hardware: it is the physical support. All the physical devices in the computer

which can be touched. For instance: wires, chips, transistors, etc.

Software: it is the logical support (non-physical). It cant be touched. The

program. Language: a set of symbols with a meaning used to communicate with the

computer. For instance: C, JAVA, Basic, etc. It allows us to make programs.

There are two types of languages: low level languages (language closer to the

machine or machine code or binary code) and high level languages (closer to the

human being)

Compiler: Translator from a high level language to binary code (0 and 1).

High level language(c++, Java) Translator Binary code

name: compiler

Operating system: Program that hides the complexity of the hardware allowing us

(the human beings) to interact with the computer through the keyboard, mouse,

printer, scanner, etc. Examples: Windows, Mac OSX, Linux, Symbian, etc.

Parameters used for comparing equipments Word length: maximum amount of bits (binary digits) that computer is able to

process in parallel

Memory capacity: amount of information that the computer is able to store

RAM random access memory (main memory)

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Prefixes commonly used in computer science:

1 byte = 8 bits

1K byte = 1024 bytes = 210 bytes

1M byte = 210 K bytes = 220 bytes

1 G byte = 210 M bytes = 230 bytes

1 T bytes = 210 G bytes = 240 bytes

Execution rate: there are several approaches. The most relevant one is just to take

the time needed to execute your program. However, there are another approaches

like the use of MIPS and MFLOPS.

MIPS vs. MFLOPS (higher-> better)

MIPS: millions of instructions per second .

= (number of instructions / execution time) X 106

()

MFLOPS: millions of floating point operations per second

Example: 2.3 x 10-23

= Number of floating operations / (execution time x 106)

()

How to build a processor

Basic computer structure. The Von Neumann

architecture

The Von Neumann architecture

It defines the concept of stored program. The programs (and data) reside in main

memory, however the unit which executes the program (the CPU) is located in

another side of the computer. Then, it is needed to communicate the main memory

with the CPU in some way. How? Using buses or wires. This bus is known as system

bus or commercially FSB (Front Side Bus). The Von Neumann architecture uses a

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single bus to perform this communication between the CPU and the Main Memory.

Besides, the system bus connects the I/O unit with the rest of the elements of the

computer (CPU and Main Memory).

CPU

It is the brain of the computer. It takes data as input and converts it to processed

information as output. The programs (or input data) reside in main memory.

The CPU is structured in two parts: Control Unit (CU) and Arithmetic Logic Unit (ALU).

CU is the brain of the brain. It commands the whole computer to execute the

instructions of a program. To do this it generates all the needed electronic signals.

ALU. It carries out all the arithmetic and logic operations. The four main types of

arithmetic operations that the ALU can perform are: addition, subtraction,

multiplication, division. The three main logical operations that the ALU can

perform are: AND, OR, NOT operations.

BAS: System BAS:

Address BASE: Contains addresses, eg. 0 1 2 3

Data BASE: Data eg. 0111100011

Control BASE: Read/Drive

Single BASE puts all of above into integration

Problems always in RAM memoryCPU: Brain. Inside CPU: have registers, dep. on Processors.

Main Memory: Storage of Computer

Functional Diagram of a CPU: CPU Architecture and Operation

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Memory

The memory of the computer is the place where the information resides. It isstructured as a set of cells. Each cell stores a single bit of information. These cells are

grouped in words which current size is 64 bits.

In order to access to the memory, an address is needed. This address identifies a

unique set of cells or words inside the memory. For instance considering a word of

size 8 bits and n possible addresses:

Address 0 00100000

Address 110011101

.

.

.

Address n-110010111

The memory can be classified in two types: main memory or primary and secondary

memory.

Primary memory consists of the computers RAM and the processor cache. This

memory is temporary storage, meaning it is erased when you turn off the

computer.

Secondary memory is permanent. This is made up of hard drives, pen drives,

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external hard disks, etc.

The Input /Output (I/O) Unit

It is the interface (something in the middle) between the computer (the CPU) and the

peripheral devices (keyboard, mouse, screen, printer, etc.). It allows us to interact

with the computer using peripheral devices. It performs the adaptation of signals

between the computer and the external world.

Programs execution - Cycle

In order to execute an instruction of a program, several phases or steps are required

by the CPU:

1st Search of the instruction located in main memory

2nd Instruction decoding: to know which instruction is

3rd Search of the operands involved in the instruction

4th Execution of the instruction

5th Storing of the result

The above five steps constitute the instruction cycle, and need to be performed for

each instruction of a program.

Historical evolution of computersMain authors John Napier

Blaise Pascal: Triangle

Leibnitz: Punching Cards

Joseph Jacquard

Charles Babbage who established the foundation of nowadays computers

Hernan Hollerit:IBM founder

Computer generations 1st Generation (1938-1952): technology ofvacuum valves Examples of machines:

ENIAC, EDVAC, EDSAC, etc.

2nd Generation (1953-1962): technology ofdiscrete transistors (not integrated

into machine). Examples of machines: IBM 7070, PDP 5, TRADIC, etc.

3rd Generation (1963-1971): technology of integrated circuits composed by

hundreds of transistors. Examples of machines: IBM 360, PDP 8 and PDP 11

4th Generation (1972-1987): technology of integrated circuits composed by

thousands of transistors, the CPU from now in one chip = microprocessor.

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Examples: Cray, Fujitsu M382, etc.

5th Generation (1987-?): technology ofintegrated circuits composed by millions

of transistors. Current machines: PCs, Workstations, CAD/CAM/CIM systems, etc.

Interesting links1. www.cern.ch

2. Use of the Wikipedia for main authors biographies

3. www.singularityu.org

4. www.isunet.edu

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