ComRing - packet driver for "network" based on serial ports version 1.20 Copyright 1997,8 by Jan Bobrowski This is free software. Use it at your own risk. Distribution unlimited. MOTIVATION The intention of ComRing is to connect more than two computers through ordinary serial ports. ComRing cable allows you to build "network" based on serial ports using one port per computer. It is slow but cheap. ComRing software also offers network interface for traditional Null-modem. It may be useful for games that don't handle serial link properly. HARDWARE Serial port was developed for computer-modem connection. It is widely used to connect two computers using null-modem cable. It consists of two units: trasmitter and receiver. They may be connected to different computers (?). The basic idea of ComRing is to organize computers in logical form of ring. Data will flow in fixed direction. A -----> B ^ | | | | v D <----- C You should prepare 3-wire ComRing cable: line DB9 DB25 TxD 3 2 transmit connected to RxD of next computer RxD 2 3 receive connected to TxD of previous computer GND 5 7 ground common for all computers DB25 DB9 _____________________________ _____________ 1 \ . T R . . . G . . . . . . / 13 1 \ . R T . G / 5 14 \ . . . . . . . . . . . . / 25 6 \ . . . . / 9 ----------------------- ------- Cable for three computers: Computer A Computer B Computer C TxD ----------- RxD TxD ----------- RxD RxD --------------------------- TxD GND ----------- GND ----------- GND Cable for four computers: Computer A Computer B Computer D Computer C TxD ----------- RxD TxD --------------------------- RxD RxD ----------- TxD RxD --------------------------- TxD GND ----------- GND ----------- GND ----------- GND You can use Null-modem cable as two-node ComRing. SOFTWARE ComRing cable for more than two computers will not work with an ordinary SLIP or PPP packet driver. You can't use it as null-modem. I wrote special packet driver (comring.com) to make it usable. It is class 1 driver - it emulates DIX ethernet (specification 1.11, basic and high-performance functions). You must install it on each computer to close circuit. To distinguish between different computers in the "network" specify a single letter, identifying your computer. It is the first parameter (and only required) to the packet driver. When you invoke `comring a' on one computer you can't use `a' (or `A') on others. This letter is used to generate ethernet address. Number of nodes (computers) is limited to 17. Syntax is: comring id [parameter]... You may use following parameters: com# com port (default: 2) baud=# baud rate (default: 115200, it may be slowed down) nodes=# maximal number of computers connected (default: 3) int=# interrupt for packet driver (hex, default: 60) If you're using nonstandard port you should specify: port=# port address irq=# irq number Example: comring A baud=9600 com1 Note: Comring is supposed to be a DOS program. It's an open question how to use it with Windows games. GAMES Most games don't use packet driver interface. They expect IPX network. You may use `pdipx' adapter (by Colin Cook) included in this package. It has been configured for DIX ethernet (command: econfig.exe pdipx.com shell:e 8137). Invoking commands may look like: comring B com1 baud=57600 pdipx game You should remember: if one computer will not work correctly, the whole network won't work.