Come Lynx with me

One of the differentiating features of the Atari Lynx was its ability to link together up to 18 Lynx devices using a set of cables. This allows for multiplayer games,

You need at least two Lynx devices and at least one ComLynx cable to make a connection. For more Lynxes you require an additional ComLynx cable for every extra Lynx. The ComLynx cable has two male connectors at either end. One end has a split cable with a female connector.

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The single male side of a new cable can be connected to the female connector and to the next Lynx at the split end. This way you can connect an potentially unlimited chain of Lynxes. The practical limit is around 18 because of communication overhead and something called “pull-ups”.

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and so on.

There were several games that used this capability for multiplayer support. Each Lynx will need a separate copy of the game. There is a possibility to game

Title Players Title Players
Awesome Golf 1-4 Pit-Fighter 1-2
Baseball Heroes 1-2 Raiden 1-2
Basketbrawl 1-2 Rampage 1-4
Battlewheels 1-6 Rampart 1-2
Battlezone 2000 1-4 Robo-squash 1-2
Bill and Ted’s Excellent Adventure 1-2 Shanghai 1-2
California Games 1-4 Super Off-Road 1-4
Checkered Flag 1-6 Super Skweek 1-2
Double Dragon 1-2 Todd’s Adventures in Slime World 1-8
European Soccer Challenge 1-2 Tournament Cyberball 2072 1-4
Gauntlet: The Third Encounter 1-4 Turbo Sub 1-2
Hockey 1-2 Warbirds 1-4
Jimmy Connors Tennis 1-4 World Class Soccer 1-2
Joust 1-2 Xenophobe 1-4
Lynx Casino 1-2 Xybots 1-2
Malibu Bikini Volleyball 1-4 Zarlor Mercenary 1-4
NFL Football 1-2

The ComLynx-able games can be recognized by the yellow triangle at the bottom-right corner of the box. This shows that players can “Lynx Up” and the maximum number of players. The game “California Games” is an exception, in that is says “1 To 2 Players” on the box, where a total number of 4 players are possible.

Todd's Adventures in Slime World - Box Front image_66F1FA20

and pay special attention to the corner.

Here is a video that shows two Lynxes connected together:

Remarks found all over the Internet:

  • “The ComLynx does not have any hardware bugs. But the format is pretty much fixed to start bit, 8 data bits, even parity, 1 stop bit. And the only sensible baud rates are 9600 and 62500. The ComLynx has a combined Rx/Tx pin and it can sense if two Lynxes transmit at the same time. … The Lynx has +5V on one pin that is enough to power up the communications cable.” – AtariAge forums
  • ComLynx was originally developed to run over infrared links (and was codenamed RedEye).[4] This was changed to a cable-based networking system before the final release.” – Wikipedia
  • “UART (for ComLynx) (fixed format 8E1, up to 62500 Bd)” – Wikipedia

Bugs in the ComLynx (from the Lynx development manual):

  • “A design error causes the power up state of the output to be TTL high, ALL code must set the TXOPEN bit in order to fix this”
  • “Well, we did screw something up after all. Both the transmit and receive interrupts are ‘level’ sensitive, rather than ‘edge’ sensitive”

Links that seemed useful to me:

Here are some observations I made, which I hadn’t read on the Internet anywhere:

  1. Some (maybe all?) ComLynx-able games can connect players while the start-menu/animations is displayed.
    In other words: as long as no player has started the game, other players can join by switching their Lynx on. Bear in mind the next observation. I always believed that the Lynxes needed to be powered on at the (near-exact) same time.
  2. When multiple Lynxes are linked together, the outsides of the chain can switch off, without disrupting the other connected Lynxes. The same goes for switching the Lynxes on at a later time (see previous point)
  3. You can disable the cartridge detection of the Lynx. In theory this should allow for multiple Lynxes to connect on one cartridge, provided that the Lynx have detection disabled and that the cartridge is read only at the startup of the game. Did anyone try this?

From the Lynx Frequently Asked Questions:

Q. What does “ComLynx” mean, exactly?
A. Some Lynx games allow multiple players to play together simultaneously. This works when each player has a Lynx game machine, and all of the machines are connected to each other via cables. The connection is the ComLynx port, and the cables are ComLynx cables. Games that support this mutiplayer simultaneous play are usually identified by the phrase “1 to N players Lynx up” on the box, the instruction manual, and/or the game card.

Q. Do all players “Lynxed up” via the ComLynx need a copy of the game being played?
A. Yes. All players need a copy of the game card.

Q. What’s the ComLynx port like?
A. There is limit of 18 players via ComLynx. In practice it may be possible to connect more units together, but to operate within specifications, the drivers in the Lynx cannot drive over more than 17 units with pull-ups on the serial ports. ComLynx runs from 300.5 to 62.5K baud. It works on a “listen and send” structure. Data transmission between Lynxes is done in the background, freeing up the CPU to run the game instead of communicating. It’s called “RedEye” in-house at Atari, named after an early idea of having Lynxes communicate with infra-red transmissions. It uses a three-wire cable (+5V/Ground/Data) and allows for bi- directional serial communications. The system frames messages in terms of 11-bit words, each consisting of a start bit, eight data bits, a parity bit, and a stop bit. The ComLynx port is used solely for communications; it can’t be used to control other aspects of the Lynx, though in theory it can be used to send signals to external devices.

Q. Sometimes a multiplayer ComLynx game will freeze up. Why?
A. A ComLynxed game will freeze if communication between the Lynxes is interrupted. If communications can be restored, the game will continue. The most common cause of this problem is a fray in one of the ComLynx cables, or a loose seating in one of the ComLynx jacks. Communication is broken, and the game “freezes”. Jiggling the cable or reseating the jacks may fix the solution temporarily, but the best cure is a new cable.

Q. I hear there’s a ComLynx port on the Atari Jaguar. How does that work? Can I connect my Lynx to it? Will there be a Lynx adaptor for the Jaguar?
A. The ComLynx port allows communication between Jaguar units and Lynx units. In theory, it would be possible to daisy-chain multiple units of either machine type for multiplayer games. At the current time, however, no such plans are in the works. Instead, it is seen as allowing Lynxes to be used as peripherals: software can be developed to allow Lynxes to be part of a Jaguar game as controllers. An adaptor to allow the Jaguar to play Lynx games is not currently planned.

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