Yup, they were the only company to get a keyboard
add-on out for the
2600...
Nooo... :)
This one was made by Dynacom (Brazil):
http://produto.mercadolivre.com.br/MLB-143147542-transforme-seu-atari-em-um…
In this page, you can see the "Dactar-Comp":
http://www.atari.com.br/historia/index.html
There was another (brazilian) model, I cannot find the proper link right
now :)