MULTI DASH is a multi-player multi-computer game for the Atari XL/XE computers. It may be played by 1-8 players, each with his own Atari XL/XE computer. The game-rules explanation is included in the program; this file contains the information about hardware connection between more computersí, and some additional details.
To play MULTI DASH, you need the following hardware:
First install 1-8 Atari XL/XE computers powered offí into the same room, each with a monitor powered oní, and ofcourse with the ORIGINAL power-supply unit, and possibly a joystick. Dončt connect any other peripherals, such as SIO2PC links, modems, audio amplifiers and such. You should also remove all unnecessary cables from your TV/monitor žTV antenna, audio outputs, other computerčs output etc. etc.í. Remember, that youčre going to connect the computers together, so you need them to be insulated - otherwise a short circuit might happen over the ground wires in a large/complicated configuration with strange devices in it.
One computer will be a "Master" system - this one will control the network. Connect a disk drive to this system, turn it on, and start the MULTIDSH.COM file žor use any other peripherals you might have to start that fileí. Disconnect the disk drive again!
Now you should connect the computers together using the hardware described below. After selecting the language, and typing in your name on the Master žyou can see the main menuí, the network is ready for starting up the other computers ž"Terminals"í. Just turn the individual systems on - theyčll boot up from a "disk drive", which is software-simulated inside the Master system. žIf youčre using some OS-ROM changes, or cartridges blocking the booting-process, you should enter the command you are commonly using to boot a disk.
After a successfull boot, the terminal should display the Login screen. žThe network is free to boot another system.í After selecting the language, and typing in the playerčs name, youčll see the main menu. While the other computers are booting, you may read the on-screen manual for playing the game, define keyboard controls žif youčve no joystickí, or send a short text messages to the other systems, which are already logged-in žthis might fail in the moments, when some other system is booting, because the network is busyí. You may do the same also on the Master system, but it might slow-down the booting process a bit.
At the bottom of every systemčs screen, therečs a red status-line indicating the terminal-number. On the Master, youčll also see which numbers are currently logged-in, and also a booting process is indicated here.
When all systems are ready, press START on the Master to begin the game. After transmission of the game-map, all systems will display a kind of "get ready" message. All players should finish manual-reading, key-definitions etc. quickly, and press FIRE in the main menu žor at the manual pagesí. The Master will display a list of Terminals, which are still not ready.
When all players are ready, the game begins. The game-rules explanation is inside the program itself, so there is no need to repeat it here... When the game is over, all systems will display the game results žthatčs in fact one of the manual pages - you can start another game-round immediatelyí.
From the main menu, you can re-enter the Login screen. Also the RESET key do the same. This should be used in the case that an other player came to the computer, and he wants to select an other language, and/or enter his own name. Itčs possible that youčll get an other Terminal-number than before! žTherečs also a choice to do a coldstart from the Login screen - do it when youčve disconnected the computer from network, rather than switching off and on.í
When the network is accidentally disconnected from your computer, when there are heavy electromagnetic fields around the cables, or when the Master did a RESET or a new Login, the activity of some Terminalžsí might be cancelled. When this happens during the game, youčll see a warning message, and the Login screen appears. But when youčre in the main menu, it might happen that the computer dončt recognize that problem - in this case you should re-enter the Login screen manually. Note that the Master does accept Login or BOOT attempts only when itčs in the main menu - not during the game, or while setting it up žsending map, waiting for all players readyí, and also not at the Login screen.
When there are more than 5 computers, or with some communication problems, the game may slow down a little bit.
The file HARDWARE.PIC does show two versions of the hardware connection a picture in Graphics mode 8í. Note that the hardware is fully compatible with an older game called "Maze of AGDAgon" žfrom The AGDA group, 1993í - any hardware working with that game should also work with MULTI DASH.
The easiest connection is shown on the right half of the picture. This version is only for 2 computers, which must be on the same table - since itčs operating directly on POKEY outputs, no long cables are allowed, and it must be handled with a care. Itčs good for first tries at home, when a friend visited you with his computer.
You need only two SIO-cables žcommonly used to connect disk drivesí, three pieces of thin wire, and a piece of insulation tape. After booting up the Master system, take the cables žbetter disconnectedí, and fix the connectors žat one end of each cableí together using the insulation tape - so that youčll see the connectorsč pins as shown on the picture. Then insert the three wires carefully to make the shown connections. Be careful not to make a short circuit, and not to bend the connectorčs pins with a too thick/hard wire. Place the assembly at a safe place on your table, where youčll not touch it, and where itčll not touch any other hardware/metal parts žbetter fix it against accidental movement by placing for example a book over the cables.í Finally plug the free ends to the two computers, and try to boot up your Terminal.
After the end of playing, first disconnect the cables, and then remove wires/tape.
The left half of picture shows a more advanced device. This is for hardware-experienced users, who wants to build a networking hardware for a larger computer meeting.
The picture shows a scheme of a small interface, which should be located close to each computer ždirectly on the connector, or connected using a single SIO-cableí. The network-cables between these interfaces are only 2-wire, and these cables may be quite long to reach all the 8-bits around a large party-room. It should work with cables up to 30m of total length žI was successfull with 21m of a cable - even non-shielded - at the Atariada 99 meetingí, but depending on the cable-type youčve used, it might work even with 100m or more. The interfaces žwhen assembled correctly ofcourse!í does provide a reasonable protection of your computers against electrostatic discharges, and other accidental voltages on the line, but still you must take care on polarity, each systemčs insulation žmentioned aboveí, and not to make a short circuit.
The function of the mentioned interface is rather simple: The P-N-P transistor does send about 4V to the line, when the POKEY data output is active; an inactive output does not interfere to the line. žThe 100nF capacitor is reducing current-peaks going back to computerčs power lines while switching.í This voltage is received by the N-P-N transistors of every interfaces ž >1V noise-rejectioní, and so the data-pulses are sent to the POKEY inputs.
The two small diodes are blocking any currents that might go into a powered-off computer, avoiding interference to other data-transmissions on the line, as well as a possible damage of POKEY inputs. The zener diode together with the 10 Ohm resistor is a protection against higher-power electrostatic discharges, or other accidental currents. The leads from the 10 Ohm resistor, and from the "-" line should go first to the zener - only from here it may continue to the rest of interface. žThis arrangement is protecting your computer in the rare event of a high-power interference on the line, avoiding the case that a connection to the zener blows up, without of disconnecting also the other circuits from the line.í Larger zener youčll use - better protection youčll have. A common 5.1V zener should be enough when the network is handled with a care, but better is a BZW06-5V8 or similar diode. žThese diodes are designed especially for protecting industrial electronics - it can blow a fuse on a 230V power line without of damaging the interface, when neccessary - but better dončt try it!í
All the mentioned protection-stuff might maybe look unnecessary, but I recommend you to allways include it into an interface youčll build. While at home itčll probably work without of protection, at large computer-meetings the cable will come across many PCčs, power-supply units, monitors, power lines, and other strange things, and XL/XE spare parts (POKEY) are nowadays quite hard to get... Safety first!!!
If you want to design your own device, you must provide the following function: All the computers žData INí must get any data sent from any other computer žData OUTí. When the output is inactive High, or when the computer is power-off, it must not interfere to othersč communications. And dončt forget about protection of your computerčs life...
Happy playing wishes you the author. My address:
Jiri Bernasek Na Hrebenkach 42 150 00 Praha 5 Czech republic