||SQL Server Tips by Burleson
The ASCII Character Set
ASCII (American Standard Code for Information Interchange) is a
seven-bit code developed by ANSI (American National Standards
Institute). The standard ASCII character set has 128 numbers that
* 0 to 31 - control codes, for
string, file or device handling.
* 32 – space.
* 48 to 57 – numbers.
* 65 to 90 - capital letters, western alphabet (bit 5 reset).
* 97 to 122 - lower case letters, western alphabet (bit 5 set).
The Extended ASCII Character Set uses the bit seven therefore adding
another 128 characters with line drawing and special symbols
(international characters, math symbols, currency symbols, simple
geometric shapes, etc.). This set has many different variations and
one solution for allowing national characters in the Extended
Character Set was to define code pages.
The above book excerpt is from:
Turbocharge Database Performance with C++ External Procedures
Joseph Gama, P. J. Naughter