Over time, several different technologies were developed including automating ordinary typebar typewriter mechanisms (such as the Friden Flexowriter), daisy wheel printers (dating from a 1939 patent, but brought to life in the 1970s by Diablo engineer David S. Lee) where the type is moulded around the edge of a wheel, and "golf ball" (the popular informal name for "typeball", as used in the IBM Selectric typewriter) printers where the type is distributed over the face of a globe-shaped printhead (including automating IBM Selectric mechanisms such as the IBM 2741 terminal).
The daisy wheel and Selectric-based printers offered the advantage that the typeface was readily changeable by the user to accommodate varying needs.
Because of its low cost at the time, the daisy wheel printer became the most successful, the method used by Diablo, Qume, Brother and Apple.
[1] Letter-quality impact printers, however, were slow, noisy, incapable of printing graphics or images[2] (unless the programmable microspacing and over-use of the dot were employed), sometimes limited to monochrome, and limited to a fixed set (usually one) of typefaces without operator intervention, though certain font effects like underlining and boldface could be achieved by overstriking.
Software did exist to (slowly) produce pie charts on such printers (and on some daisywheels the dot was reinforced with metal to cope with extra wear).