February 17, 2026
Ctrl your feelings
Four Column ASCII (2017)
Hidden keyboard trick explains the Escape key—and the comments go feral
TLDR: A four‑column ASCII chart explains why pressing Ctrl with keys triggers hidden control actions like Escape, sparking big “aha” moments. Commenters then brawled (politely) over whether this is built into ASCII or just a terminal convention, while nostalgia and confusion over old keyboards and xterm displays fueled the fun.
A humble four‑column chart of ASCII—the old 7‑bit code behind your keyboard—just sent the internet’s keyboard nerds into a frenzy. The big reveal: pressing Ctrl+[ gives you Escape because Ctrl wipes the top bits of the character, turning “[” into the control version. Cue the choir of “aha!” as folks connect it to why Ctrl‑J is newline and Ctrl‑D ends a session. One commenter even joked Windows files look like they’ve been glitter‑bombed with “^M”.
But the real spice? Is this “Ctrl magic” part of ASCII or a terminal hack? One camp insists it’s by design—case flipping and control keys are just simple bit tricks. Another fires back that ASCII never said “Ctrl this, get that”; old terminals made it happen by chopping bits. Keyboard archaeologists showed up with receipts: “Teletype layout has parentheses on 8 and 9,” and early Apple IIs literally put a “bell” over the G—yes, it would beep. Meanwhile, the mod‑librarian energy of dang linked past debates like a greatest hits tour, and confused newcomers asked why their xterm shows different control glyphs. The vibe? Nostalgia meets nitpicking—a perfect storm of “I knew this,” “Actually…,” and “Wait, what am I looking at?” with links back to the OG post here.
Key Points
- •ASCII is a 7-bit encoding; a four-column, 32-row layout clarifies relationships among characters.
- •Control characters occupy the first 32 positions and can be entered in terminals via CTRL combinations.
- •CTRL+[ yields ESC because ESC and '[' share the same five low bits; CTRL clears the top bits.
- •This behavior can be described as a bitwise AND that zeroes all but the lowest five bits of the typed character.
- •Windows CR+LF line endings cause ^M to appear when viewing files with tools that show control characters (e.g., cat -A).