Control Codes and Keys
In the old days, holding down the Ctrl key electrically zeroed the left 2 bits of the 7 bit ASCII code, allowing one to enter the first 32 characters of the ASCII code, irrespective of the shift key. These non-printing characters were used primarily for device/printer control.
Software flow control: XON/XOFF are control characters used in data transmission. XOFF is used by a receiving device as a way to let the transmitting device know it needs to stop transmitting. When the device is ready to recommence, the XON character is sent.
XOFF is achieved by pressing Ctrl + s , and XON is achieved by pressing Ctrl + q .
Ctrl + g should get an audible bell sound out of most terminals!
Abbr. | Description | Dec | Hex | Oct | Keys |
---|---|---|---|---|---|
NUL | Null | 0 | 00 | 000 | Ctrl + @ |
SOH | Start of Heading | 1 | 01 | 001 | Ctrl + a |
STX | Start of Text | 2 | 02 | 002 | Ctrl + b |
ETX | End of Text | 3 | 03 | 003 | Ctrl + c |
EOT | End of Transmission | 4 | 04 | 004 | Ctrl + d |
ENQ | Enquiry | 5 | 05 | 005 | Ctrl + e |
ACK | Acknowledgment | 6 | 06 | 006 | Ctrl + f |
BEL | Bell | 7 | 07 | 007 | Ctrl + g |
BS | Backspace | 8 | 08 | 010 | Ctrl + h |
HT | Horizontal Tab | 9 | 09 | 011 | Ctrl + i |
LF | Line Feed | 10 | 0a | 012 | Ctrl + j |
VT | Vertical Tab | 11 | 0b | 013 | Ctrl + k |
FF | Form Feed | 12 | 0c | 014 | Ctrl + l |
CR | Carriage Return | 13 | 0d | 015 | Ctrl + m |
SO | Shift Out | 14 | 0e | 016 | Ctrl + n |
SI | Shift In | 15 | 0f | 017 | Ctrl + o |
DLE | Data Link Escape | 16 | 10 | 020 | Ctrl + p |
DC1 | XON / Device Ctrl 1 | 17 | 11 | 021 | Ctrl + q |
DC2 | Device Ctrl 2 | 18 | 12 | 022 | Ctrl + r |
DC3 | XOFF / Device Ctrl 3 | 19 | 13 | 023 | Ctrl + s |
DC4 | Device Ctrl 4 | 20 | 14 | 024 | Ctrl + t |
NAK | Neg. Acknowledgment | 21 | 15 | 025 | Ctrl + u |
SYN | Synchronous Idle | 22 | 16 | 026 | Ctrl + v |
ETB | End of Transmit Block | 23 | 17 | 027 | Ctrl + w |
CAN | Cancel | 24 | 18 | 030 | Ctrl + x |
EM | End of Medium | 25 | 19 | 031 | Ctrl + y |
SUB | Substitute | 26 | 1a | 032 | Ctrl + z |
ESC | Escape | 27 | 1b | 033 | Ctrl + [ |
FS | File Separator | 28 | 1c | 034 | Ctrl + \ |
GS | Group Separator | 29 | 1d | 035 | Ctrl + ] |
RS | Record Separator | 30 | 1e | 036 | Ctrl + ^ |
US | Unit Separator | 31 | 1f | 037 | Ctrl + _ |
DEL | Delete | 127 | 7f | 177 | Ctrl + ? |