Computers Communicating ``` Name: Billy Status: student Grade: 6-8 Location: FL Country: USA Date: Fall 2011 ``` Question: How do computers talk to each other? Replies: Hi Billy, Great question! Much like how we talk to each other, computers have a common language. For most of us it's English. In addition, computers follow what is called protocol, much like how we follow rules and etiquette. The computer language is made up by an electrical signal and it is either 5 volts or 0 volts. This can be represented as a [1] or a [0]. This one or zero is what is called a bit in the binary language. Binary, meaning two bits of information. The language can be defined so that [1] means "yes" and [0] means " no". But computers can process multiple bits per given time. So adding more bits, gives us more words. Say two bits of information: [00], [01], [10], [11]. Each of these can mean "yes", "no", "maybe", "I do not know". Adding even more, say 3 bits, we get more combinations of bits and hence more words: [000] = no [001] = yes [010] = maybe [011] = I do not know [100] = start [101] = stop [110] = wait [111] = ignore So now we have a group of codes which are made up of binary information. When computers talk to each other, they each have what is called an address like your home address or much like a name. Pretend we have more combinations of bits that will give us four names: [Bob], [Mary], [Frances], [Tom]. We can now send a string of information that would say: [Send to] [Sent from] [Command or message] [End of message] So a conversation could look like this: [Send to Bob] [Sent from Mary] [Hi Bob!] [End of message] [Send to Mary] [Sent from Bob] [Good morning Mary!] [End of message] [Send to Bob] [Sent from Mary] [Please call Frances and Tom] [End of message] [Send to Mary] [Sent from Bob] [OK] [End of message] [Send to Frances AND Tom] [Sent from Bob] [It's time for our meeting!] [End of message] Of course there are many rules and procedures that help maintain conversations between computers, but the above is the basis for communication between a switched-network of computers. Hope that helps! Let me know if it does not. -Alex Viray Billy Today, computers can talk to each other over metallic wires, fiber optic cable or by radio link (called "wireless"). Tomorrow, who knows.... Computers use "protocols" that define the language that they speak to each other with. All computers on a network segment must speak the same language so they can trade and understand each other's messages. Computers are assembled in Local Area Networks (LAN) or Wide Area Networks (WAN). LAN connected computers connect to other computers in the local area, like on the floor of a building, in a private residence, or in a department of a larger enterprise. WAN connects LANs to other distant LANs on the World Wide Web, or connect branch offices to the central office or some other distantly connected LAN. LAN protocols include: Ethernet (Most used) Token Ring IEEE 802.11 wireless Virtual LAN (VLAN) WAN protocols include: ATM (Asynchronous Transfer Mode) MPLS (Multi-Protocol Label Service) (My favorite) Frame Relay PPP (Point-to-Point Protocol) OSPF (Open Shortest Path First) BGP (Border Gateway Protocol) (Can be used on world-wide networks) RIP (Routing Information Protocol) ...And you get the idea... This is a whole career full of acronyms. So if you want to start digging into it, there is an awful lot of information on-line. Start by Googling "LAN" and I would choose the Wikipedia sites, although that is a steep start, So you might be able to find other sites for beginners. Sincere regards, Mike Stewart Click here to return to the Computer Science Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs