Computer ???

Adhi Harmoko S, M.Komp

What is a computer?A computer is a machine that stores data (numbers, words, pictures), interacts with devices (the monitor screen, the sound system, the printer), and executes programs.A computer program is a sequence of instructions and decisions that the computer carries out to achieve a task.Programs describe specific actions.A computer executes very simple instructions.A computer executes instructions very rapidly.A computer is a general purpose machine

What is a computer?A computer must be programmed to perform tasks. Different tasks require different programs.A computer program consists of a finite sequence of very basic operations.A typical operation may be one of the following:

put a red dot onto a certain screen positionsend the letter B to the printerget a number from a certain location in memoryadd up two numbersif this value is negative, stop the programrepeat this instruction ten times

What is a computer?Hardware

Physical devices of computer systemSoftware

Programs that run on computers

"Buses" allow components to pass data to each other

Hardware Components of a Typical Computer

PeripheralDevices

Central ProcessingUnit (CPU)

Memory

Hardware Components of a Typical Computer -- CPU

Central Processing Unit (CPU)performs the basic operationsconsists of two parts:

Arithmetic / Logic Unit (ALU) - data manipulationControl Unit - coordinate machine’s activities

MemoryPeripheralDevices

Central ProcessingUnit (CPU)

PeripheralDevices

Central ProcessingUnit (CPU)

Memory

Hardware Components of a Typical Computer -- Memory

Main Memoryholds programs and datastores bits in fixed-sized chunks: “word” (8, 16, 32, or 64 bits)each word is stored in a cell, which has a unique addressthe cells can be accessed in any order =>random-access memory or “RAM”

Hardware Components of a Typical Computer -- Memory

A bit: 0 or 1A word: chunk of bits (8, 16, 32 or 64 bits)

a byte = 8 bitsa kilobyte = 210 bytes = 1024 bytes a megabyte = 1024 KB = 220 bytes = 1,048,576 bytesa gigabyte = 1024 MB = 230 bytesa terabyte = 1024 GB = 240 bytes

PeripheralDevices

Central ProcessingUnit (CPU)

Memory

Hardware Components of a Typical Computer -- Peripherals

Peripheral devices –communicate with the outside worldstore data long term

PeripheralDevices

Central ProcessingUnit (CPU)

Memory

Input/Output (I/O)Input: keyboard, mouse, microphone, scanner, sensors (camera, infra-red), punch-cardsOutput: video, printer, audio speakers, etc

Communicationmodem, ethernet card

Hardware Components of a Typical Computer –Peripheral Devices that Communicate with the Outside World

Hardware Components of a Typical Computer –Peripheral Devices that Store Data Long Term

Secondary (mass) storageStores information for long periods of time as filesExamples: hard drive, floppy disk, tape, CD-ROM (Compact Disk Read-Only Memory)

Features of Computers – SpeedCPU Speed

One cycle Example Clock

CPU clock speed: in cycles per second ("hertz")Example: 700MHz Pentium III, 3.2GHz P4

but different CPU designs do different amounts of work in one clock cycle (e.g. P4 vs G5)“flops” (floating-point operations per second)“mips” (million instructions per second)

communication between CPU, memory and peripheral devices depends on main board (a.k.a. "motherboard") design

Examples: Intel 3.60GHz Pentium-4 works on a 200MHz bus speed50MHz, 60MHz, 66MHz, 100Mhz, 133MHz, 200MHz, 266MHz, and risingQuad-pumped multiplies by 4

Features of Computers – SpeedSystem-Clock/Bus Speed

Features of Computers – SpeedMemory-Access Speed

RAMabout 50ns (1 nanosecond = a billionth of a second), and getting fastermay be rated with respect to “bus speed’’ (e.g., PC-100, PC-133, etc)

Cache memoryfaster than main memory (less than 20ns access speed), but more expensivecontains data which the CPU is likely to use next

Features of Computers – Speed Peripheral-Device Speed

Mass storageExamples:

3.5in 1.4MB floppy disk: about 500kb/sec at 300 rpm (revolutions per minute)3.5in hard disk: average seek time about 8.5 microseconds, and 7,200 rpm

CommunicationsExamples: modems at 56 kilobits per second, and network cards at 10 or 100 megabits per second

I/OExamples: ISA, PCI, IDE, SCSI, ATA, USB, etc....

Most system failures are due to software flaws rather than hardware

Features of Computers -- ReliabilityFactors that affect reliability:

heat, ventilation, “over-clocking”, power surges

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Modes of communicationParallel communication:

all the bits are transferred at the same time each bit on a separate line

Serial communication: one bit at a time

Modems (MOdulator-DEModulator)

Remote Computer

ModemHome

Computer

ModemDigitalData

DigitalData

Audio signalphone lines

TypesLocal Area Networks (LAN)

Computers in an organizationExample: the PCs in the lab

Long Haul Networks Separated by hundreds or thousands of milesPhysical wires, telephone lines, satellites, etc

Example: Internet “backbone”

Computer Networks

Computer Networks – Method of Communication

Each computer has an addressExample: IP address of www.fisika.ui.ac.id is 152.118.167.2

A sender computer transmits data through the network in packets; each packet is tagged with the destination and return address

When data is too big to fit in one packet, the sender computer can split the data into several packets, labeled in sequence

Computer Networks – Method of Communication (cont)

The packets are sent via links from computer to computer (“routing”) Each intermediate computer receives and retransmits the message (“hops”)

The packets do not necessarily arrive in the order in which they were sent

The recipient computer puts the packets in correct sequence and retrieves the data

Computer and SupportJaringan Komputer LAN / WLAN

Computer and SupportSistem Input Data

Computer and SupportSistem Pemroses Data

Computer and SupportSistem Output Data

Computer and SupportSistem Penyimpan Data

Computer and SupportFiber Optic Communication

Technology Information Todaywireless communication

What is programming?A computer program tells a computer, in very detail, the sequence of steps that are needed to fulfill a task.The act of designing and implementing these programs is called computer programming.Programmers develop computer programs to make computers perform new tasks.A professional computer scientist or software engineer does a great deal of programming.The activity of programming is an important part of science

What is Algorithm?

AlgorithmAlgorithm: A set of instructions describing how to do a task (or process)

eureka!

ProgramProgram: : C++C++

Programming LanguagesMachine language

“Natural language” of computer componentMachine dependent

Assembly languageEnglish-like abbreviations represent computer operationsAssembler converts it to machine language

High-level languageAllows for writing more “English-like” instructions

Contains commonly used mathematical operationsCompiler converts it to machine language

InterpreterExecute high-level language programs without compilation

Computer and SupportSoftware: Operating System

Computer and SupportSoftware: Aplikasi

Computer and SupportSoftware: Development

Computer ProductMultimedia

Computer Productsms, w@p, gprs communication

Computer ProductSistem Control berbasis Web