which resides in the
read/write
memory. This section discusses
only the
ROM
routine.
Extended ASCII encompasses
I-byte
character codes, with
possible values of 0 to 255, an extended code for certain extended
keyboard functions, and functions handled within the keyboard
routine
or
through interrupts.
Character Codes
The character codes described later are passed through the BIOS
keyboard routine to the system
or
application program.
A"
-1
"
means the combination
is
suppressed in the keyboard routine.
The codes are returned in the
AL
register. See "Characters,
Keystrokes, and Color" later in this manual for the exact codes.
4-34
lOl/102-Key
Keyboard