ASCII/IBM PC Extended ASCII Display Characters
Strictly speaking, the ASCII character set only includes values up to 127 decimal (7F hex). However, when the IBM PC was developed, the video card contained one byte for each character in the 80x25 character display. Gee...what to do with that extra bit per character? Why not invent 128 new characters, for line-drawing and special symbols? The result, of course, was the extended ASCII character set for the IBM PC. The chart below shows (most of) the characters that can be generated by the display in the original IBM PC.
Microsoft Windows ® has a different notion about what the high-order (upper 128) characters are, as shown in the table below.