UNIX

Maybe a bit strange when I first heard the name " UNIX " , the difference is when we hear the word DOS or WINDOWS that is not foreign to the ear more so for those who have worked using computers in their daily work in the office or at home . UNIX does not vary with the type of DOS or WINDOWS operating system or operating system installed on the computer . Lies the difference is generally installed on a UNIX workstation in a computer network is installed on the computer and rarely stand alone . Microsoft Press Computer Dictionary 3rd Edition Operating System defines as :
The software that controls the allocation and usage of hardware resources such as memory , central processing unit ( CPU ) time , disk space , and peripheral devices. The operating system is the foundation on roomates applications are built . Popular operating systems include Windows 95 , Windows NT , Mac OS , and UNIX . Also called executive . Acronym : OS .
Grace Todino , John Strang and Jerry Peek in his book entitled " Learning the UNIX Operating System" states that the operating system as :
A collection of program that controls and organizes the resources of a computer system . These resources Consist of hardware components such as terminals , printers and line printers , and the software programs that tell the computer to perform specific tasks .
So Operating System - abbreviated OS - at its core is a program that consists of small programs that are used to control all the resources - more commonly referred to as resource - available to a computer system and the operation of the foundation program application .
UNIX emerged through a long process . UNIX milestone began in 1969 when Ken Thompson , Dennis Ritchie and several colleagues started working on something that will be UNIX . The name " UNIX " is actually intended for a game on MULTICS previously written " UNICS " as an abbreviation of UNiplexed Information and Computing System. During the 10 years of the development of UNIX is basically done in the company AT & T Bell Labs , USA . Early versions of UNIX were labeled
 3

" Version n " or " Nth Edition " in its user guide ( manual ) and is intended for the DEC PDP - 11 machines ( 16 bit ) and VAX ( 32 bit ) . Some versions include :
 V1 (1971 ) - the first version of UNIX ( VI ) in the form of assembler on the PDP - 11/20 . Including the file system , fork ( ) , Roff , ed . Used as a word processing ( text processor ) . Command pipe ( ) first appeared on the UNIX V2 .

 V4 ( 1973 ) - Re-written in C language , which is the most important moment in the history of the Operating System; meant to be paired UNIX ( ported ) on a new hardware for months and the changes can be done easily . C language was initially designed for the UNIX operating system so that there is a strong synergy between C and UNIX .

 V6 (1975 ) - The first version of UNIX available outside Bell Labs , especially in a university environment . This is also the beginning of the popularity of UNIX . UNIX variants labeled 1.xBSD ( PDP - 11 ) derived from this version .

 V7 (1978 ) - This is the "last true UNIX " . Bourne - Bourne shell creator - say UNIX V7 is an increase of all that initiate and follow UNICES . It was equipped with the C language by Brian Kernighan and Dennis Ritchie ( K & R ) , uucp , Bourne shell . V7 installed on the VAX 32V . V7 kernel size of 40 Kbytes and the price is only $ 100 for university and $ 21,000 for individuals .

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examples of java program 2

/*
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 * and open the template in the editor.
 */
package asd1;

import java.util.Scanner;

/**
 *
 * @author RaJo
 */
public class soal4 {
   
    public static void main(String[] args) {
       
        Scanner in = new Scanner(System.in);
       
        String kata[][]=new String[5][10];
       
        kata[0][0]="hadiah";
        kata[0][1]="penghargaan, angpao, bonus, cendera mata, kado, pemberian";

       
        kata[1][0]="moderen";
        kata[1][1]="baru, mutakhir, segar, trendi";

        kata[2][0]="canggih";
        kata[2][1]="rumit, maju, kompleks, hebat, pelik";

        kata [3][0]="sulit";
        kata [3][1]="sukar, susah,";
       
        kata [4][0]="mati";
        kata [4][1]="wafat, meninggal, tewas";
       
        System.out.println("pilihan kata: ");
        for (int i = 0; i < kata.length; i++) {
            System.out.println(i+1+"."+kata[i][0]);    
           
        }
       
        boolean bol=false;
        while (bol == false){
           
        System.out.println("masukan pilihan: ");      
        int pil = in.nextInt();
       
        System.out.println("hasil: "+kata[pil-1][1]);
    }
   

       
    }
}

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examples of java program 1

/*
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 * and open the template in the editor.
 */
package asd1;

/**
 *
 * @author RaJo
 */
public class soal2 {
    public static void main(String[] args) {

        char [] c ={'A','B','C',' ','D','E','F'};
    for(int I=0; I< c.length ; I++){
           System.out.println(c[I]);
           }
       System.out.println("selesai");
}
    }

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examples of java program

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package asd1;

/**
 *
 * @author RaJo
 */
public class soal1 {
   
    public static void main(String[] args) {
         int a[] = new int[11];
       
        for (int i = 0; i < a.length; i++) {
            a[i]=i;          
        }
       
        for (int i = 0; i < a.length; i++) {
            System.out.println(a[i]);
           
        }

   
}
}

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TRANSMISSION CONTROL PROTOCOL DARPA INTERNET PROGRAM PROTOCOL SPECIFICATION

TRANSMISSION CONTROL PROTOCOL

                         DARPA INTERNET PROGRAM                       

  PROTOCOL SPECIFICATION

                            1.  INTRODUCTION

The Transmission Control Protocol (TCP) is intended for use as a highly reliable host-to-host protocol between hosts in packet-switched computer communication networks, and in interconnected systems of such networks.

This document describes the functions to be performed by the Transmission Control Protocol, the program that implements it, and its interface to programs or users that require its services.

1.1.  Motivation

  Computer communication systems are playing an increasingly important  role in military, government, and civilian environments.  This  document focuses its attention primarily on military computer  communication requirements, especially robustness in the presence of  communication unreliability and availability in the presence of  congestion, but many of these problems are found in the civilian and  government sector as well.

  As strategic and tactical computer communication networks are  developed and deployed, it is essential to provide means of  interconnecting them and to provide standard interprocess  communication protocols which can support a broad range of  applications.  In anticipation of the need for such standards, the  Deputy Undersecretary of Defense for Research and Engineering has  declared the Transmission Control Protocol (TCP) described herein to  be a basis for DoD-wide inter-process communication protocol  standardization.

  TCP is a connection-oriented, end-to-end reliable protocol designed to  fit into a layered hierarchy of protocols which support multi-network  applications.  The TCP provides for reliable inter-process  communication between pairs of processes in host computers attached to  distinct but interconnected computer communication networks.  Very few  assumptions are made as to the reliability of the communication  protocols below the TCP layer.  TCP assumes it can obtain a simple,  potentially unreliable datagram service from the lower level  protocols.  In principle, the TCP should be able to operate above a  wide spectrum of communication systems ranging from hard-wired  connections to packet-switched or circuit-switched networks.

                                                                [Page 1]

                                                          September 1981 Transmission Control Protocol Introduction

  TCP is based on concepts first described by Cerf and Kahn in [1].  The  TCP fits into a layered protocol architecture just above a basic  Internet Protocol [2] which provides a way for the TCP to send and  receive variable-length segments of information enclosed in internet  datagram "envelopes".  The internet datagram provides a means for  addressing source and destination TCPs in different networks.  The  internet protocol also deals with any fragmentation or reassembly of  the TCP segments required to achieve transport and delivery through  multiple networks and interconnecting gateways.  The internet protocol  also carries information on the precedence, security classification  and compartmentation of the TCP segments, so this information can be  communicated end-to-end across multiple networks.

                           Protocol Layering

                        +---------------------+                        |     higher-level    |                        +---------------------+                        |        TCP          |                        +---------------------+                        |  internet protocol  |                        +---------------------+                        |communication network|                        +---------------------+

                                Figure 1

  Much of this document is written in the context of TCP implementations  which are co-resident with higher level protocols in the host  computer.  Some computer systems will be connected to networks via  front-end computers which house the TCP and internet protocol layers,  as well as network specific software.  The TCP specification describes  an interface to the higher level protocols which appears to be  implementable even for the front-end case, as long as a suitable  host-to-front end protocol is implemented.

1.2.  Scope

  The TCP is intended to provide a reliable process-to-process  communication service in a multinetwork environment.  The TCP is  intended to be a host-to-host protocol in common use in multiple  networks.

1.3.  About this Document

  This document represents a specification of the behavior required of  any TCP implementation, both in its interactions with higher level  protocols and in its interactions with other TCPs.  The rest of this

[Page 2]

September 1981                                           Transmission Control Protocol                                                            Introduction

  section offers a very brief view of the protocol interfaces and  operation.  Section 2 summarizes the philosophical basis for the TCP  design.  Section 3 offers both a detailed description of the actions  required of TCP when various events occur (arrival of new segments,  user calls, errors, etc.) and the details of the formats of TCP  segments.

1.4.  Interfaces

  The TCP interfaces on one side to user or application processes and on  the other side to a lower level protocol such as Internet Protocol.

  The interface between an application process and the TCP is  illustrated in reasonable detail.  This interface consists of a set of  calls much like the calls an operating system provides to an  application process for manipulating files.  For example, there are  calls to open and close connections and to send and receive data on  established connections.  It is also expected that the TCP can  asynchronously communicate with application programs.  Although  considerable freedom is permitted to TCP implementors to design  interfaces which are appropriate to a particular operating system  environment, a minimum functionality is required at the TCP/user  interface for any valid implementation.

  The interface between TCP and lower level protocol is essentially  unspecified except that it is assumed there is a mechanism whereby the  two levels can asynchronously pass information to each other.  Typically, one expects the lower level protocol to specify this  interface.  TCP is designed to work in a very general environment of  interconnected networks.  The lower level protocol which is assumed  throughout this document is the Internet Protocol [2].

1.5.  Operation

  As noted above, the primary purpose of the TCP is to provide reliable,  securable logical circuit or connection service between pairs of  processes.  To provide this service on top of a less reliable internet  communication system requires facilities in the following areas:

    Basic Data Transfer    Reliability    Flow Control    Multiplexing    Connections    Precedence and Security

  The basic operation of the TCP in each of these areas is described in  the following paragraphs.

                                                                [Page 3]

                                                          September 1981 Transmission Control Protocol Introduction

  Basic Data Transfer:

    The TCP is able to transfer a continuous stream of octets in each    direction between its users by packaging some number of octets into    segments for transmission through the internet system.  In general,    the TCPs decide when to block and forward data at their own    convenience.

    Sometimes users need to be sure that all the data they have    submitted to the TCP has been transmitted.  For this purpose a push    function is defined.  To assure that data submitted to a TCP is    actually transmitted the sending user indicates that it should be    pushed through to the receiving user.  A push causes the TCPs to    promptly forward and deliver data up to that point to the receiver.    The exact push point might not be visible to the receiving user and    the push function does not supply a record boundary marker.

  Reliability:

    The TCP must recover from data that is damaged, lost, duplicated, or    delivered out of order by the internet communication system.  This    is achieved by assigning a sequence number to each octet    transmitted, and requiring a positive acknowledgment (ACK) from the    receiving TCP.  If the ACK is not received within a timeout    interval, the data is retransmitted.  At the receiver, the sequence    numbers are used to correctly order segments that may be received    out of order and to eliminate duplicates.  Damage is handled by    adding a checksum to each segment transmitted, checking it at the    receiver, and discarding damaged segments.

    As long as the TCPs continue to function properly and the internet    system does not become completely partitioned, no transmission    errors will affect the correct delivery of data.  TCP recovers from    internet communication system errors.

  Flow Control:

    TCP provides a means for the receiver to govern the amount of data    sent by the sender.  This is achieved by returning a "window" with    every ACK indicating a range of acceptable sequence numbers beyond    the last segment successfully received.  The window indicates an    allowed number of octets that the sender may transmit before    receiving further permission.

[Page 4]

September 1981                                           Transmission Control Protocol                                                            Introduction

  Multiplexing:

    To allow for many processes within a single Host to use TCP    communication facilities simultaneously, the TCP provides a set of    addresses or ports within each host.  Concatenated with the network    and host addresses from the internet communication layer, this forms    a socket.  A pair of sockets uniquely identifies each connection.    That is, a socket may be simultaneously used in multiple    connections.

    The binding of ports to processes is handled independently by each    Host.  However, it proves useful to attach frequently used processes    (e.g., a "logger" or timesharing service) to fixed sockets which are    made known to the public.  These services can then be accessed    through the known addresses.  Establishing and learning the port    addresses of other processes may involve more dynamic mechanisms.

  Connections:

    The reliability and flow control mechanisms described above require    that TCPs initialize and maintain certain status information for    each data stream.  The combination of this information, including    sockets, sequence numbers, and window sizes, is called a connection.    Each connection is uniquely specified by a pair of sockets    identifying its two sides.

    When two processes wish to communicate, their TCP’s must first    establish a connection (initialize the status information on each    side).  When their communication is complete, the connection is    terminated or closed to free the resources for other uses.

    Since connections must be established between unreliable hosts and    over the unreliable internet communication system, a handshake    mechanism with clock-based sequence numbers is used to avoid    erroneous initialization of connections.

  Precedence and Security:

    The users of TCP may indicate the security and precedence of their    communication.  Provision is made for default values to be used when    these features are not needed.

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example array in java 5

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

/**
 *
 * @author DK
 */
import java.util.*;
public class nomor5list {
           // number of elements in array
   public static void main(String [] args)
   {
       Scanner in = new Scanner(System.in);
       Chain list = new Chain();
       list.add(0, new Character('a'));
       list.add(1, new Character('b'));
       list.add(2, new Character('d'));
       list.add(3, new Character('g'));
       list.add(4, new Character('a'));
       list.add(5, new Character('a'));
     
       for(int i = 0;i<6;i++){
           System.out.println("pilihan = "+list.get(i));
       }
     
       int a =list.indexOf(new Character('a'));
       System.out.println("jumlah a ="+a);
     
      }
}

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example array in java 4

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

/**
 *
 * @author DK
 */
import java.util.Scanner;
public class nomor4list {
 
    public static void main(String[] args)
    {
        String[][]kata = {{"baju","kemeja","jaket",},{"pesawat","helikopter","jet"},{"mobil","formula","nascar"},{"buku","kamus","atlas"},{"gunung","bukit","lembah"}};
        Chain list = new Chain();
        list.add(0, "kemeja");
        list.add(1, "helikopter");
        list.add(2, "nascar");
        list.add(3, "kamus");
        list.add(4, "gunung");
//      
//        for(int i=0;i<kata.length;i++)
//        {
//            System.out.println("" + (i+1)+ "." + kata[i][0]);
//        }
        System.out.println("pilihan :");
        System.out.println("0.baju");
        System.out.println("1.pesawat");
        System.out.println("2.mobil");
        System.out.println("3.buku");
        System.out.println("4.gunung");
        Scanner scan = new Scanner(System.in);
        System.out.println("masukan pilihan : ");
        int pilihan = scan.nextInt();
        System.out.println("Hasil : " + list.get(pilihan));
    }
}

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