PETSCII
PETSCII (PET Standard Code of Information Interchange) is the variation of the ASCII character set used in Commodore's 8-bit home computers, starting with the Commodore PET from 1977 and including the VIC-20, Commodore 64, Plus/4, C16 and C128.
As well as a subset of standard ASCII spanning codes 32–90, i.e. punctuation and upper-case letters, PETSCII consists of a range of block graphic characters, such as boxes, circles, quarter circles, straight and angled lines of varying thickness, crosses, checkered 'flags', playing card colors, etc, allowing quite sophisticated graphic patterns to be built without resorting to user-defined characters or bitmapped graphics (both of which the PET lacked). There were also cursor and screen control codes, such as "HOME", "CLR", "RVS ON", and "RVS OFF" (the latter two activating / deactivating reverse-video character display).
Two special control codes provided for toggling between the power-on default upper-case & graphics character set, and the alternative lower- & upper-case set (which also contained some graphic characters although not the full range). In the VIC-20, C64, and later machines, color codes supplemented the other screen control codes. Obviously, as for all computers based on non-standard-ASCII character sets, software conversion was needed when exchanging text files with, and telecommunicating with, standard ASCII systems.
See also: ATASCII