Editing Commodore 64 (section)

==Layout==
The keyboard layout is from the [[Commodore VIC-20]], with lineage back to the Commodore PET line of office computers.

The alphanumeric area is 16.25u wide, with Return and Del keys far right. To the right of it, there is a column of four [[function keys]]. The function keys have odd numbers: even numbers are acquired with Shift.

There are two [[Cursor_keys#Commodore_PET_.281977.29|cursor keys]] right of the right Shift key. They are Down and Right respectively but reversed with Shift. Together they can be operated with three fingers on one hand.
:[[File:Cursor keys--Commodore PET.svg]]

The C64 has two character sets in ROM, called [https://en.wikipedia.org/wiki/PETSCII PETSCII], based on the 1963 version of ASCII with a ← instead of _ and ↑ instead of ^. Commodore also put the £ sign instead of \. The default ''unshifted'' set is all-caps.
In BASIC mode, pressing Shift+Commodore switches to/from the ''shifted'' set which has lower-case characters also. The switch changes only a pointer to a different place in the character ROM: upper-case chars become lower-case, and graphics chars become upper-case. Upper and lower case characters in the shifted set are swapped compared to regular ASCII.

Most of the character set is occupied by graphics characters: line drawing, blocks, playing card colours and pi, and "reverse text mode" forms of those.
The non-reversed graphic characters are printed on the front (later: on top) of the alphabetic and symbol keys, They are accessible with the Commodore modifier, and Shift (unshifted set only).
Commodore + <number> changes the text colour, and for entering/leaving "reverse text mode".

There are a few different country-specific keyboards with different layouts but instead of different keycaps the keys that differed from the English norm had stickers with new legends.
These C64s came with different kernal ROMs with different character-scanning routines. The character set did also not support all letters so the character ROMs had character graphics in some code spaces replaced with others.