PETSCII

PETSCII (PET Standard Code of Information Interchange), also known as CBM ASCII, is the variation of the ASCII character set used in Commodore (CBM)'s 8-bit home computers, starting with the PET from 1977 and including the VIC-20, C64, Plus/4, C16 and C128.^*

As well as a subset of standard ASCII spanning codes 32–90, i.e. punctuation and uppercase 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, with its non-relocatable ROM-stuck character definitions and text-only video chip).

Included in PETSCII 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). The control codes appeared in program listings as reverse-video graphic characters, although some computer magazines, in their efforts to provide more clearly readable listings, pretty-printed the codes using their actual names, like the above examples. The screen control codes were essentially similar to escape codes for text based computer terminals.

Two special control codes were provided for toggling between the power-on default uppercase+graphics character set, and the alternative lower+uppercase 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.

(* The Amiga computers used standard ASCII. )

See also: ATASCII