Dot-Matrix Printout

Prompt

Identify

Text and images break into [round dots] arranged in regular rows. Coarse dot grids give curves [stepped edges], while uneven ink makes some dots faint.

Principle

An impact printhead¹ drives selected pins against an [inked ribbon], transferring small ink marks onto paper. Printhead movement and paper feeding position these marks to build letters and pictures.

Example

Digital Equipment Corporation: LA36 DECwriter II, 1974.

Try it out

Examine an impact-printer receipt with a magnifier, then copy one letter onto squared paper using only dots.

Background

Dot-matrix impact printing became common in the 1970s as computers needed affordable paper output. Unlike printers with fixed letter shapes, these machines assembled characters from individually selected dots. A moving printhead struck an inked ribbon while the paper advanced between printed lines. Continuous stationery² often had perforated edges that helped feed it through the machine. Graphics-capable models could also place dots to form diagrams and pictures. More pins and overlapping passes³ could improve detail, but printing took longer. The visible grid records both the printer's mechanical spacing and its instructions.

Distinction

Halftone printing uses dot patterns to reproduce tones, often by varying dot size. Impact dot-matrix printing builds marks with pin strikes, including the letters themselves.

Aftermath

The printout shows how a visible image can emerge from discrete marks constrained by mechanical movement.

Question

Sources

• Wikipedia: Dot matrix printing ↗