Many of Carter's fonts were created to address specific technical challenges, for example those posed by early computers. Charter was created to use a minimal number of design elements to fit in a small memory space on early computers, a problem that had expired even before he finished the design. The bold versions of Verdana and Georgia are also unusually bold, almost black. Carter noted that, "Verdana and Georgia ... were all about binary bitmaps: every pixel was on or off, black or white ... The bold versions of Verdana and Georgia are bolder than most bolds, because on the screen, at the time we were doing this in the mid-1990s, if the stem wanted to be thicker than one pixel, it could only go to two pixels. That is a bigger jump in weight than is conventional in print series." Some of Carter's early font digitisations would later be revisited: Monotype released an expanded version of Charter and Font Bureau expanded versions of Georgia, Verdana, Big Caslon and others. Earlier in his career, Bell Centennial was created to be legible in telephone directories, even when printed on cheap paper at small sizes.