What does the code before ASCII 0x20 mean?

1, (Nul) 0 0000 0x00 | (SP) 32 0040 0x20 |, 64 0100 0x40 | ` 96 0140 0x60 (empty)

2 、( soh) 1 000 1 0x 0 1 |！ 33 00410x21| a65010/0x41| a9701410x61(at the beginning of the title

3. (STX) 2 0002 0x02 | "34 0042 0x22 | b6601020x42 | b9801420x62 (at the beginning of the text)

4. (ETX) 300030x03 | # 3500430x23 | C6701030x43 | C9901430x63 (text result)

5. (EOT) 4 0004 0x04 | $36 0044 0x24 | D6801040x44 | d10001440x64 (end of transmission)

6. (enq) 5 0005 0x05 |% 37 0045 0x25 | e69 0105 0x45 | e101450x65 (query character)

7 、( ack)60006 0x 06 | & amp； 38 0046 0x26 | F7001060x46 | F10201460x66 (Confirmation)

8. (BEL) 7 0007 0x07 | 39 0047 0x27 | G 710107 0x47 | G1030147 0x67 (alarm)

9. (BS) 800100x08 | (400500x28 | H720100x48 | h10401500x68).

10，(ht)9 00 1 1 0x 09 |)4 1 005 1 0x 29 | I 73 0 1 1 1 0x 49 | I 105 00。

1 1, (nl)10/kloc-0 | * 42 0052 0x2a | j7401120x4a | j1060/kloc.

12, (vt)110/30x0b |+4300530x2b | k750130x4b | k1070/kloc-0.

13, (NP) 12 00 14 0x0C |, 4400540x2c | l7601140x4c | l10801.

14，(Cr) 13 00 15 0x0d |-45 0055 0x2d | M77 0 1 15 0x4d | m 109 0 155 0x6d(enter)。

15, (so)1400160x0e | .46 00560x2e | n7801160x4e | n10.

16，(Si) 15 00 17 0x0f |/47 0057 0x2f | O79 0 1 17 0x4f | O 1 1 1 1 165438。

17, (dle)1600200x10 | 04800600x30 | P8001200x50 | p1kloc-0/20/kloc-0.

18，(DC 1) 17 002 1 0x 1 1 | 1 49 006 1 0x 3 1 | q 8 1 065438。

19, (dc2)18 00220x12 | 250 00620x32 | r8201220x52 | r1kloc-0/40/kloc-.

20. (dc3)1900230x13 | 35100630x33 | s8301230x53 | s1630x73 (equipment control

2 1, (dc4) 20 00240x14 | 4 52 00640x34 | t8401240x54 | t11601640x74

Extended reading:

ASCII code:

1, ascii code is the most widely used character set and its coding in computers at present. It is the American Standard Code for Information Interchange (ASCII) formulated by the American National Bureau of Standards (ANSI) and designated as an international standard by the International Organization for Standardization (ISO), which is called the ISO 646 standard. Applicable to all Latin letters, ASCII code has two forms: 7-bit code and 8-bit code.

No.2.0 ~ No.32 and No. 127 (* * 34) is a control character or a special communication character, such as control characters: LF (line feed), CR (carriage return), FF (page feed), DEL (deletion), BS (backspace), BEL (ringing) and so on. Special communication characters: SOH (prefix), EOT (suffix), ACK (acknowledgement), etc.

3.33 ~ 126 (***94) is a character, of which 48 ~ 57 is 0 ~ 9 Arabic numerals; Numbers 65 ~ 90 are 26 uppercase English letters, numbers 97 ~ 122 are 26 lowercase English letters, and the rest are punctuation and operation symbols.