# Introduction to the Internet

If you are (or want to be) a new Internet user, and Arachne is your first encounter with the technical terms describing Internet protocols and applications and their configuration, configuring Arachne will not be an easy task for you. This page contains short explanations of the most frequently used words in the Arachne documentation.

### The Internet

The Internet is a worldwide network of computers based on the TCP/IP protcol. It allows you to use many different services based on various Internet protocols. The Internet is also known as the "Information highway".

The most popular services are WWW and eMail, based on protcols called HTTP, SMTP and POP3. Other well known services include FTP, Usenet (news - protocol NNTP), Telnet and IRC. If you don't understand what words like "service" or "protocol" mean, just picture all this stuff as alternatives or enhancments to well known electronic communication services like televison, voice phone or fax.

There are also other experimental services, like Internet Phone, See-You-See-Me, PointCast network, ICQ or Internet Radio, which are not generaly understood as Internet standards. Some of the Internet protocols, like Gopher or Finger are remnants from an earlier chapter in the history of the Internet. It is very interesting and if you are interested in it, try to get a book about the Internet.

### TCP/IP

A family of communication protocols used on the Internet. Something like the engine in a car: users don't have to know how it works, they only have to know which kind of fuel they need, and where to go if something goes wrong.

Most important among TCP/IP protocols are TCP (transmission control protocol), IP (internet protocol) and UDP (user datagram protocol). Pieces of data transported by TCP/IP are called packets.

Advanced operating systems (like Unix) implement TCP/IP as a basic system service (on the same level as other I/O operations); in small systems like DOS, TCP/IP must be integrated into the application. This is why configuring Arachne is so confusing: you are configuring both TCP/IP and the browser (and if you are using a modem, then a PPP dialer also) all in one program! With Arachne, you are provided with a complete network solution, which together with the operating system fits onto one floppy and can be booted from it.

TCP/IP was designed for permanently connected computers; if you want to connect using a phone line and modem, you will need to establish a SLIP or PPP protocol between your Internet provider and your computer to transfer TCP/IP packets to your computer.

### WWW

WWW stands for World Wide Web. It is a system of online hypertext pages, located on many servers all around world. Pages are written in the HTML language and linked to each other. Pages can also contain links to objects of different types, like soundtracks, movies, live audio and video broadcasting, etc.

Arachne is a WWW client - a program which can request, download and view HTML pages. The WWW uses a protocol called HTTP.

The only mass communication technology that is as easy to use as the WWW is probably television. Users of the World Wide Web are expected only to be able to read and to know how to use a mouse to select hypertext links, nothing more.

### eMail

eMail, E-mail, or email are various shortened versions of "electronic mail".

Electronic mail is simply an exchange of text messages (which can contain attached encoded files) between Internet users. Arachne can currently send and receive simple eMail messages, using protocols called SMTP (sending eMails) and POP3 (downloading eMail from mailbox). Every user of Internet mail is assigned a unique address of format username@domain. Your username does not have to be identical to your login name. The domain is usually (but not always) the name of your provider's mail server.

Having a personal eMail address is probably as common today as having a personal telephone number.

### PPP

Point to Point Protocol. A protocol which transfers TCP/IP packets through your modem and connects your computer to the Internet. There are three ways to authenticate a PPP connection: the first option is to ask for manual login (like if you are calling a BBS system) whereafter the PPP protocol starts without further verification (you will see a bunch of characters like ~,#,!, etc. in the terminal window). Arachne can do an automatic login to an internet service provider, if you configure it correctly. The second option is called Password Authentication Protocol (PAP) and the third one is Challenge Authentication Protocol (CHAP). The PPP dialer shipped with Arachne currently supports PAP, but CHAP is already supported by the latest release of DOSPPPD.

### URL

Universal Resource Locator. You have probably seen announcments like "Visit internet homepage of Some Company at http://www.somecompany.com/. This is a typical URL. It is an identifier for resources that are accessible by WWW browser, most often an HTML page accessible using the HTTP protocol. In Arachne, you must first connect to the Internet. Once you are connected, just press the F3 key, enter the URL you want and press Enter.

The URL syntax is protocol://[username[:password]@]hostname[:port][/URI]

URI is a shortcut for Uniform Resource Identifier, and it is in fact very often just a filename of a document or program located on the WWW server.

### OpenDOS

We described Arachne as a "DOS application". This means that in principle, Arachne can run under various types of operating systems that are compatible with MS-DOS 3.3: MS-DOS up to 6.22, Windows 95, OS/2, DR-DOS, NovellDOS, DOSEMU under Linux, SoftPC under NextStep (all these options were tested). However, we recommend that you use Caldera OpenDOS, a clone of DOS, which is free for non-commercial use. Even inexperienced users can easily configure OpenDOS using its built-in setup utility. And you can easily download latest patches and upgrades of OpenDOS from the Caldera Website.

OpenDOS is the latest member of Digital Research's CP/M development line: CP/M ... DR-DOS ... Novell DOS ... Caldera (DR)OpenDOS.

### DOS memory

When you are using MS-DOS, your computer with an Intel compatible processor starts in "real mode": this means that even if you have a Pentium, your computer generally behaves like a PC XT when you boot DOS, i.e., only 1 MB of RAM can be used directly by your programs, and the largest executable program size can be up to 640 kB (but is usually less, since various device drivers must also be present in memory). More memory than 1 MB can be accessed only as storage space for data. It is called XMS or EMS memory.

But you are likely to have a 386 or better processor which can be switched to "protected mode" (also called "32bit" mode) to access all the memory. From DOS, you can do this, for example, by using a DPMI driver. You are probably asking why Arachne is a real mode application, running only in the first 640 kB of your PC's memory. The reason is that the golden era of DOS ocurred on real mode computers, and most development tools, libraries, and helper applications feel best in real or "V8086" (also called "Virtual") mode. Developing applications for protected mode DOS is a much more complex task.

Arachne, as a real mode application, is a very small program and fits onto a single floppy: compare this to protected mode applications, written in object-oriented languages. They are ten times larger and take forever to download from the Internet. Arachne was developed mainly for PCs with a 80286-, 80386-, or 80486-compatible CPU and with only several MB of RAM, where real mode DOS applications perform much better than Windows applications. On Pentium P5/P6 (trademark of Intel), AMD K5/K6 or various 80586 and 80686 machines with more than 8 MB of memory, real mode applications are not able to use the full potential of the system. However, you can use an extended memory manager like EMM386 or QEMM to optimize a "virtual DOS machine" on your 386 or better computer. This is very efficient and actually much faster than the operating systems which are expected to run on these machines. Using DOS on Pentium class computers probably can give you more "real-time" feel then using any other OS.

### RAM disk

DOS is able to use the extra memory of your system as a virtual file system, called a RAM disk. If your PC has more than 8 MB of memory, you should definitely think about configuring such a RAM disk to increase the speed of your DOS applications, including Arachne. This will probably give you the fastest operating system ever available: while 32bit operating systems use your hard disk as virtual memory, with 16bit DOS you can use your memory as a very fast hard disk. This can increase, for example, the speed of JPEG decompression in Arachne, etc. The problem is that the content of a RAM disk is lost when you turn off your computer. Configuring Arachne to run from a RAM disk (by copying its home directory to the RAM disk) but using directories for mail and downloaded files on the hard disk can be a good solution.

Check your system manual or configuration utility for information on how to configure a RAM disk on your PC.

This list will be more extensive in future releases of Arachne