Sounds cool, where can I download the source code and test this system?
It was not exactly something you could compile and run yourself. On the other hand, if you have time, you can go ahead and implement any of the systems Chaum proposed (you'll probably want to scroll down to the 80s and 90s):
Really though, Chaum's digital cash ideas involved building infrastructure around existing currency to protect privacy and prevent certain kinds of fraud (e.g. double spending, identity theft). Chaum was not trying to bring down the world's economic system with digital cash, he was just trying to give people a more secure way to pay for things electronically. The failure of his system in the real world was likely linked to the strong pushback by the US government against the use of good cryptography by "commoners."