ASCII 17
ASCII 17 is Device Control 1 (XON) — the control character DC1.
Every representation
| Character | DC1 (not printable) |
| Name | Device Control 1 (XON) |
| Decimal | 17 |
| Hexadecimal | 0x11 |
| Octal | 0021 |
| Binary | 00010001 |
| HTML entity |  |
| Escape sequence | \x11 |
| Unicode | U+0011 |
| Keyboard | Ctrl+Q |
| Group | Control character |
What it is for
Also called XON. Resumes a paused transmission. This is what Ctrl+Q sends, and why a terminal that has mysteriously frozen often unfreezes when you press it.
Where the number comes from
Codes 0 to 31 were reserved for control: instructions to a teleprinter rather than characters to print. Code 17 is Ctrl+Q because the Ctrl key was originally wired to clear the top two bits of whatever you typed, mapping the letter Q at 81 down to 17.
Frequently asked questions
What is ASCII 17?
Device Control 1 (XON) (DC1), a control character. In hexadecimal it is 0x11, in octal 0021, and in binary 00010001.
How do I type ASCII 17?
Press Ctrl+Q in a terminal. In a string literal you can write it as \\x11 in most languages.
Is ASCII 17 printable?
No. Codes 0 to 31 and 127 are control characters — they were instructions to a teleprinter rather than marks on paper, and most terminals show nothing for them.
Nearby codes
- ASCII 10 — LF
- ASCII 11 — VT
- ASCII 12 — FF
- ASCII 13 — CR
- ASCII 14 — SO
- ASCII 15 — SI
- ASCII 16 — DLE
- ASCII 18 — DC2
- ASCII 19 — DC3
- ASCII 20 — DC4
- ASCII 21 — NAK
- ASCII 22 — SYN
- ASCII 23 — ETB
- ASCII 24 — CAN
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