Link 2 7800s together?

[SoundGammon]

I've always wondered if 2 7800s could be linked through the expansion port that was designed to run a laser disc player and such?

 

Be neat to see a football game where each player has a seperate screen and maybe 2 players on each side!

[+Karl G]

Since joystick ports can be read/write, in theory this could be done by linking them via the second joystick port instead.

[Synthpopalooza]

There's also 4 port adapters too.

[Lynxpro]

On 5/20/2022 at 7:50 AM, Synthpopalooza said:

There's also 4 port adapters too.

Are you referring to MultiJoys? Because those certainly do not connect to the Expansion Port.

 

Joystick Port #2 has bandwidth to accomplish this task. After all, the 7800 Keyboard plugged into it and its proprietary chip could handle keyboard input, a daisy-chained joystick, and also connect up to SIO Port devices. Curt* said he didn't have the resources to reverse-engineer it, which is why he pushed for using a PIA and a POKEY to handle SIO via the XM.

 

Theoretically, if one were so inclined, one could design a PCB with a modern [WDC] 6551 - if they wanted to remain period-authentic - [or use a NOS Synertek, Rockwell, NCR, etc 6551 from BITD - which could implement RS232 and thus do null modem connections.  

 

 

*Curt also speculated Atari Corp might've tentatively planned to design an adapter cable for Joystick Port #2 to connect the 7800 to a MIDI Adapter to make MIDI Maze 7800 possible [they had announced MIDI Maze for it before the 7800 and all other legacy Atari platforms were cancelled in 1992 to focus on the Jaguar]. He didn't have any concrete proof of it though.