The address of this routine is found in the initial channel information table.
All of the printing to the main part of the screen, the lower part of the screen and the printer is handled by this set of routines.
This routine is entered with the A register holding the code for a control character, a printable character or a token.
|The current print position.
|CP " "
|If the code represents a printable character then jump.
|Print a question mark for codes in the range +00 to +05.
|And also for codes +18 to +1F.
|Base of the control character table.
|Move the code to the DE register pair.
|Index into the table and fetch the offset.
|Add the offset and make an indirect jump to the appropriate subroutine.