Wait for next key from the keyboard.
Try to get a key from the key buffer. This routine waits until a key is found if no key is immediately available.
No conditions.
Carry true.
A contains the character or expansion token.
Other flags corrupt.
All other registers preserved.
The next key is read from the key buffer and translated using the appropriate key translation table. Expansion tokens are not expanded but are passed out for the user to deal with, as are normal characters. Other Key Manager tokens (shift lock, caps lock and ignore) are obeyed but are not passed out.