Portmadoc
From Festipedia, hosted by the FR Heritage Group
The original name c.1821 was Port Madock or Portmadock, but this changed to Portmadoc, the name generally used from c.1840 to 1974 whilst Porthmadog has since 1974 been, and currently is, the offical title. The differences are purely matters of Welsh grammar - the pronounciation is much the same.
The are a number of local interest sites, amongst which is this site
There is also a look at the nautical side of the town in an article entitled Portmadoc Maritime taken from another website.