A dot matrix ink or bubble jet-type desktop printer is adapted to be connected to a personal computer by an RS-232 serial connector, and is able to simultaneously print on both sides of a sheet of paper. The double-sided printer includes a platen-less paper transport system which secures a sheet of paper to be printed in a substantially rigid plane with both sides of the paper exposed to printing. The paper transport system includes pick-up pinch roller assemblies arranged in contacting, opposed, counter rotating fashion, and tension roller assemblies, spaced-apart from the pinch roller assemblies which cooperate to define a substantially rigid plane between the sets of roller assemblies in which the paper is tensioned. Two print head carriage assemblies, each including a print head, are provided, in mirror-image relationship, on either side of the paper plane. Processor controlled electronic printer control circuitry includes parallel pipelined data paths for providing front and back page printer information to the separate print heads, so as to effectuate simultaneous printing on both sides of a piece of paper.