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ASCII (American Standard Code for Information Interchange) is a standard character encoding used in telecommunication. The ASCII pronounced ‘ask-ee’ , is strictly a seven bit code based on English alphabet. ASCII codes are used to represent alphanumeric data . The code was first published as a standard in 1967. it was subsequently updated and published as ANSI X3.4-1968, then as ANSI X3.4-1977 and finally as ANSI X3.4-1986. Since it is a seven bit code , it can at the most represent 128 characters. it currently defines 95 printable characters including 26 upper case letters (A to Z) , 26 lower case letters , 10 numerals (0 to 9) and 33 special characters including mathematical symbols, punctuation marks and space character. They represent text in, telecommunications equipment, and devices. These include numbers, upper and lowercase English letters, functions, punctuation symbols, and some other symbols. In total, there are 256 ASCII characters, and can be broadly divided into three categories: ASCII control characters (0-31 and 127)ASCII printable characters (32-126) (most commonly referred)Extended ASCII characters (128-255)Below are the ASCII values of printable characters (33, 126):CharacterCharacter NameASCII code CharacterCharacter NameASCII code CharacterCharacter NameASCII code!Exclamation point33 AUppercase a65 aLowercase a97“Double quotation34 BUppercase b66 bLowercase b98#Number sign35 CUppercase c67 cLowercase c99$Dollar sign36 DUppercase d68 dLowercase d100%Percent sign37 EUppercase e69 eLowercase e101ersand38 FUppercase f70 fLowercase f102‘apostrophe39 GUppercase g71 gLowercase g103(Left parenthesis40 HUppercase h72 hLowercase h104)Right parenthesis41 IUppercase i73 iLowercase i105*asterisk42 JUppercase j74 jLowercase j106+Plus sign43 KUppercase k75 kLowercase k107,comma44 LUppercase l76 lLowercase l108–hyphen45 MUppercase m77 mLowercase m109.period46 NUppercase n78 nLowercase n110/slash47 OUppercase o79 oLowercase o1110zero48 PUppercase p80 pLowercase p1121one49 QUppercase q81 qLowercase q1132two50 RUppercase r82 rLowercase r1143three51 Suppercases83 sLowercase s1154four52 TUppercase t84 tLowercase t1165five53 UUppercase u85 uLowercase u1176six54 VUppercase v86 vLowercase v1187seven55 WUppercase w87 wLowercase w1198eight56 XUppercase x88 xLowercase x1209nine57 YUppercase y89 yLowercase y121:colon58 ZUppercase z90 zLowercase z122;semi-colon59 [Left square bracket91 {Left curly brace123Greater-than sign62 ^caret94 ~tilde126?Question mark63 _underscore95 @At sign64 `Grave accent96 So what’s before 33 and beyond 126?ASCII values before 32 (0-31) are control characters. A character code is often used in in-band signaling as a reference point in a set of characters to avoid adding additional symbols to the text.At 32, we have space, it is included as printed characters, however, it’s not wrong to say space could also serve as a control character.At 127, we have DEL (delete), which is a control character.After 127, (128-255), we have Extended ASCII characters representing mathematical and other symbols that are not represented as keys and are not used in general.Below are the ASCII values of control characters (0-31, 127):CharacterCharacter NameASCII Code CharacterCharacter NameASCII Code CharacterCharacter NameASCII CodeNULLNull character00 VTVertical tab11 SYNSynchronous idle22SOHStart of header01 FFForm feed12 ETBEnd of trans. Block23STXStart of text02 CRCarriage return13 CANcancel24ETXEnd of text03 SOShift out14 EMEnd of medium25EOTEnd of transmission04 SIShift in15 SUBsubstitute26ENQenquiry05 DLEData link escape16 ESCescape27ACKacknowledge06 DC1Device control 117 FSFile separator28BELbell07 DC2Device control 218 GSGroup separator29BSbackspace08 DC3Device control 319 RSRecord separator30HTHorizontal tab09 DC4Device control 420 USUnit separator31LFLine feed10 NAKNegative acknowledge21 DELdelete127My Personal Notes
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