The keyboard device is a read-only device with a handler that supports the following CIO functions:
OPEN CLOSE GET CHARACTERS GET RECORD GET STATUS (null function)
The Keyboard Handler can produce the following error statuses:
$80 -- [BREAK] key abort. $88 -- end-of-file (produced by pressing [CTRL] 3).
The Keyboard Handler is one of the resident handlers. It has a set of device vectors starting at location E420.
The keyboard can produce any of the 256 codes in the ATASCII character set (see Appendix F). Note that a few of the keyboard keys do not generate data at the Keyboard Handler level. These keys are described below:
[/|\] – The ATARI key toggles a flag that enables/disables the inversion of bit 7 of each data character read. The Screen Editor editing keys are exempted from such inversion, however.
CAPS – The [CAPS/LOWR] key provides three functions:
[SHIFT][CAPS/LOWR] -- Alpha caps lock. [CNTRL][CAPS/LOWR] -- Alpha [CTRL] lock. [CAPS/LOWR] -- Alpha unlock.
