VT100摘要

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Table 2-1: 7-Bit ASCII Code Table

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 7-Bit Code ExtensionEquivalent

C1 Character         (EscapeSequence)

 

9/11                1/11  5/11

CSI                 ESC    [

 

8/15                1/11  4/15

SS3                ESC    O

 

8/4                 1/11  4/4

IND                 ESC    D

In general, youcan use the above code extension technique in two ways.

1.    You can express any C1 control characteras a 2-character escape sequence whose second character has a code that is 40(hexadecimal) and 64 (decimal) less than that of the C1 character.

2.    You can make any escape sequence whosesecond character is in the range of 4/0 through 5/15 one byte shorter byremoving the ESC andadding40 (hexadecimal) to the code of the second character. This generates an8-bit control character.

2.5.2 ControlSequences

A control sequencestarts with CSI (9/11), followed by one or more ASCII graphic characters. ButCSI (9/11) can also be expressed as the 7-bit code extension ESC [ (1/11,5/11). So you can express all control sequences as escape sequences whosesecond character code is [ (5/11). For example, the following two sequences areequivalent sequences that perform the same function. (They cause the display touse 132 columns per line rather than 80).

9/11 3/15 3/3 6/8

CSI  ?    3    h

 

1/11 5/11 3/15 3/3 6/8

ESC  [    ?    3   h

Whenever possible,you should use CSI instead of ESC [ to introduce a control sequence. CSIuses one less byte than ESC [, so you gain processing speed. However, youcan only use a sequence starting with CSI in an 8-bit environment (because CSIis a C1 control character).