About ENQ

Integer ASCII code: 5
Binary code: 0000 0101
Octal code: 5
Hexadecimal code: 05
Group: control
Seq: ^E

Unicode symbol: , int code: 9221 (html &#9221) hex code: 2405 (html &#x2405)


Enquiry is a signal, which has a purpose of initiating a response at the receiving end, in order to make sure that it's still available.

Let's find out the meaning of enquiry in computer communications. Here enquiry means a transmission-control character that is intended to get the reply from the receiving station, with which was established a connection. Basically, enquiry is a signal that is purposed to initiate a response at the receiving end, in oder to make sure that it is still there. The reply is represented in an answer-back code to the exact terminal that sent the WRU (who are you) signal. The reply can contain station identification, type service equipment, and the current status of the remote station.

Teletype Model 33 answer-back drum (brown, lower center left) for implementing the function of coding inquiry response message.

There were some teleprinters, which had in their possession a "programmable" drum. It could keep approximately a 20 or 22 character message. The encoding of the message on the drum was performed by breaking down tabs off the drum. A sequence like this could be sent straight to the one, who would receive an enquiry signal, if it was possible. The other option was just to press the "Here is" key on the keyboard.

An enquiry character was possessed by the 5-bit ITA2. ASCII and EBCDIC, which were developed later, have adopted it as well.

In the 1960s, DEC decided to deactivate the function of answerback on Teletype Model 33 terminals. This happened because it wasn't compatible with the correct use of the paper-tape reader and binary data punch. Despite this fact, the DEC VT100 terminals, created starting from 1978 answered to enquiry using an answerback message, that could be customize to any user. Their successors have successfully adopted it.


input value base type output hash
ENQ char MD5 8bb6c17838643f9691cc6a4de6c51709
ENQ char SHA1 8dc00598417d4eb788a77ac6ccef3cb484905d8b
5 dec MD5 e4da3b7fbbce2345d7772b0674a318d5
5 dec SHA1 ac3478d69a3c81fa62e60f5c3696165a4e5e6ac4
00000101 bin MD5 4eb0e9e1d6f1580598baa36f2b828bbe
00000101 bin SHA1 7973ed24df29504b35693071f084768fb6892df6
0000 0101 bin MD5 beafb066f6a62aa90fa61fa04dfb035b
0000 0101 bin SHA1 ab6951b2f4030ac5ccc0ab5f8cf195176a1bbe2d
5 oct MD5 e4da3b7fbbce2345d7772b0674a318d5
5 oct SHA1 ac3478d69a3c81fa62e60f5c3696165a4e5e6ac4
05 hex MD5 751d31dd6b56b26b29dac2c0e1839e34
05 hex SHA1 28a5c2818590ee3c4d5d93a448190f3397144303
0x05 hex MD5 2964ef546789dceffbea8db80eb34ced
0x05 hex SHA1 2fee0d789cea022f61e53c60ae2474686baab72a
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 2018 © Dmytro Koshovyi. Ukraine, Mykolayiv.