Green bar paper
The green-and-white striped continuous-form paper that computer output came on for decades.
Greenbar was the standard stock of the machine room: continuous, perforated, tractor-fed paper with alternating green and white bands running across the page. The stripes were not decoration but a reading aid — they let the eye track a row of figures straight across the wide 132-column printouts without losing the line. The format, usually 15 × 11 inches, fed through line and dot-matrix printers in endless folded stacks. After printing, a decollator split the copies and the edges were burst off. When offices moved to A4 and cut sheets, greenbar became a nostalgic emblem of the mainframe era.