It appears that the particular variety of extended ASCII that I want is actually called Code Page 437 as opposed to the more popular ISO 8859-1. The reason I wasn't seeing the right characters in OS X ...

Several of my passwords have extended ASCII characters in them (like Æ or µ). In Windows I typed them by holding ALT and keying in the 3 number code (ALT+198). But I'm diving into Ubuntu and ...