ASCII Control Characters
34 charactersThe 33 control characters (codes 0-31 and 127) were designed for hardware signaling in teletype and serial communication systems. Characters like CR (13) and LF (10) control line breaks, HT (9) inserts tabs, BEL (7) rings the terminal bell, and ESC (27) starts escape sequences. Most are obsolete except CR, LF, HT, and ESC.
| DEC | HEX | Symbol | Name | |
|---|---|---|---|---|
| 0 | 00 | NUL | Null character | |
| 1 | 01 | SOH | Start of Heading | |
| 2 | 02 | STX | Start of Text | |
| 3 | 03 | ETX | End of Text | |
| 4 | 04 | EOT | End of Transmission | |
| 5 | 05 | ENQ | Enquiry | |
| 6 | 06 | ACK | Acknowledge | |
| 7 | 07 | BEL | Bell, Alert | |
| 8 | 08 | BS | Backspace | |
| 9 | 09 | HT | Horizontal Tab | |
| 10 | 0A | LF | Line Feed | |
| 11 | 0B | VT | Vertical Tabulation | |
| 12 | 0C | FF | Form Feed | |
| 13 | 0D | CR | Carriage Return | |
| 14 | 0E | SO | Shift Out | |
| 15 | 0F | SI | Shift In | |
| 16 | 10 | DLE | Data Link Escape | |
| 17 | 11 | DC1 | Device Control One (XON) | |
| 18 | 12 | DC2 | Device Control Two | |
| 19 | 13 | DC3 | Device Control Three (XOFF) | |
| 20 | 14 | DC4 | Device Control Four | |
| 21 | 15 | NAK | Negative Acknowledge | |
| 22 | 16 | SYN | Synchronous Idle | |
| 23 | 17 | ETB | End of Transmission Block | |
| 24 | 18 | CAN | Cancel | |
| 25 | 19 | EM | End of medium | |
| 26 | 1A | SUB | Substitute | |
| 27 | 1B | ESC | Escape | |
| 28 | 1C | FS | File Separator | |
| 29 | 1D | GS | Group Separator | |
| 30 | 1E | RS | Record Separator | |
| 31 | 1F | US | Unit Separator | |
| 32 | 20 | ␠ | Space | |
| 127 | 7F | DEL | Delete |