7800basic and the 2600 Keyboard Controller

[MAC-42]

On a whim, I was looking at the pinouts for the 2600 keyboard controller last night. Am I correct in thinking that it can be used as-is with 7800basic? (That is, 7800basic shouldn't need changes to accommodate it.) Looks to me like the keyboard matrix could be implemented with combined controller functions. For instance, keypad button 1 on the player 2 port could be activated using:

if joy1up && joy1fire1 then...

Just wondered if this was correct.

[Rybags]

Not sure that description in the link is right - the Atari documented method as used on the computer should also be applicable to 2600 & 7800.

 

The 4 directional pins can be configured as outputs - to read each row in turn you select it then the values are read from fire button + 2 Pot inputs to give the state of the selected keys.

[+RevEng]

Its a bit more involved, as Rybag suggests. This thread has an example for bB, and the reading routine near the end of the program should equally apply to 7800basic.

 

You should also first turn off the 2-button joystick mode that 7800basic enables by default for that port. You should be able to do this for port 0 with "INPT1=$f0:SWCHB=4" and for port 1 with "INPT3=$f0:SWCHB=8"

 

Unfortunately I don't have a keyboard controller, so all of my info is theoretical.

[MAC-42]

Thanks for the info, folks. Again, this was just a thought experiment. Maybe someone will find this useful someday.