March 15, 2026
One extra line, endless debate
IBM, sonic delay lines, and the history of the 80×24 display
Did IBM decide your screen? Fans fight over the missing line, punch cards, and dollar bills
TLDR: IBM’s dominance set the 80×24 screen standard, and the IBM PC added a 25th line—possibly for handy function key labels. Commenters clash over market forces versus tech myths, crack jokes about dollar-bill-sized punch cards, and demand the “real” IBM PC origin story.
A nerdy history bomb just dropped: the classic 80×24 screen wasn’t a “laws of physics” thing—it was IBM flexing its market muscle. The internet is buzzing as a new blog says the 1971 IBM 3270 terminal set the 80×24 norm, and the IBM PC later added one more line, making 80×25 the PC standard. Cue chaos. One commenter swears that extra line existed so you could slap function key labels on top, pointing to this IBM BASIC screenshot. Another romantic sigh: “Deeply fascinated by these historical threads”—because yes, the vibes are immaculate.
Drama alert: Folks who believed tech limits (TVs, memory, magic ratios) forced the size are getting roasted by the revelation that market standardization did the heavy lifting while weird sizes (31×11! 133×64!) faded away. Then II2II derails the thread into a conspiracy-fueled ask for the “real” IBM PC origin story—early microcomputers like the 5100 and the DataMaster get name-dropped like it’s a Netflix docuseries waiting to happen. The comedy crown goes to thakoppno’s chain-of-blame: punch cards modeled on census cards modeled on dollar bills—so your terminal is basically… money-shaped? Meanwhile, veltas drops a cheeky modern hot take: resurrect shift-register memory as a budget move in 2026. The crowd is split between history nerds, corporate-power skeptics, and keyboard archaeologists—and it’s glorious.
Key Points
- •IBM’s 3270 (1971) established the 80×24 terminal standard due to IBM’s market dominance.
- •IBM PC displays later added a line, making 80×25 the PC-world standard.
- •DEC’s VT100 (1978) used 80×24 and sold over a million units, reinforcing 80×24—not 80×25—as the prevailing terminal size.
- •Mid-1970s terminals exhibited many screen sizes, indicating technology did not force a specific dimension; standardization and market forces did.
- •Claims that 80×25 arose from TV aspect ratios and 2K RAM constraints are refuted: VT100 wasn’t 80×25 and didn’t fit in 2K due to extra per-line storage.