Extended Binary Coded Decimal Interchange Code
Extended Binary Coded Decimal Interchange Code (usually referred to by its acronym, EBCDIC) is an encoding for various glyphs (written forms such as letters, numbers, etc) into 8-bit numeric form.
It was devised by IBM for use in the IBM System/360 line of computers. With the success of System/360, and the creation of many plug-compatible peripherals, etc, for it, it became widespread. It has since been mostly replaced by ASCII.
The supported character set includes not only numbers, letters (upper- and lower-case) but also punctuation, and a few other special-purpose characters, like '*', '=', etc. It also does include non-printing characters used for control of printing terminals - tab, line feed, carriage return, etc.
It did not include quite a few others that ASCII has made popular - '@', '#', '^', '|', etc; this was a source of problems later, in trying to move programming languages that used them to IBM machines. These have been added later in various extensions, but support is not universal.
It also did not assign all alphabetic characters to a single range, which meant that simple tests like ((c >= 'A') && (c <= 'Z')) could return 'true' when fed some non-alphabetic characters.