Final answer:
The two main functions performed by a drum in the printing process are conditioning the drum for writing and transferring toner to the paper, specifically in laser printers and copiers using xerography.
Step-by-step explanation:
The two main functions performed by a drum in the printing process are: a) Conditioning the drum for writing and transferring toner to the paper. The drum plays a crucial role in both creating the image to be printed and then transferring that image onto paper. In the context of laser printing, xerography - a dry copying process based on electrostatics - outlines a series of steps including the charging of a photoconducting drum, creating a positive charge duplicate of the image, attracting toner to the positively charged areas of the drum, and then transferring the toner to the paper. Afterwards, the paper with the electrostatically held toner is passed through heated pressure rollers to melt and permanently fuse the toner to the fibers of the paper.