Attention article en cours de rédaction.
The insides of a HuCard aren't as exciting as you may have thought. The 'business end' of a HuCard consists of a super-thin PCB with two (or more) glop-top chips on it, flipped upside down and glued in place. The rest of the card is just to make it larger and allow space for pretty labels. Some cards have a raised section where the label is printed. These allow the PCB to be larger and encroach on the label space. Without this raised bubble platform the label space is greatly diminished, and we can't have that. In some rare cases HuCards may have batteries inside - the Tennokoe Bank and Populous are two with batteries - but normally it's to allow more space for more ROM or RAM chips, like Street Fighter or the Arcade Card Pro.