Hi,
It's pretty widely accepted that the first digital was the Pulsar P1 released in April of 72. However, the article may have been referring to a curious claim by a well known crackpot named Dr. Nakamatsu who claimed to have invented the first digital in the 50's (though there doesn't appear to be any physical evidence to support this):
viewtopic.php?f=60&t=5954#p38251I've seen it written that Casio supports this claim for some reason, which is probably why this article is connecting Casio to the claim of being involved with the first digital:
http://www.kirainet.com/english/doctor-nakamatsu/So, I wouldn't say that the article is entirely wrong, it's just based upon sketchy claims.
-abe.