When the interrupt routine detects a key press it calls a routine called
KEYCLICK in the sound driver which produces an audible
click. This routine is only called if the EXOS variable
KEY_CLICK is zero. Thus setting this variable to a
nonzero value will disable key click.
Autorepeat is controlled by two EXOS variables. DELAY_KEY
which is the delay until autorepeat starts and RATE_KEY
which is the delay between each repetition of the key. Both of these are
in units of 1/50 seconds. DELAY_KEY should always be longer
than RATE_KEY and if DELAY_KEY is zero then
autorepeat is disabled.
There are sixteen logical programmable function keys numbered 0 to 15. Keys 0 to 7 refer to the basic function keys, 8 to 15 are the shifted versions. Any one of these may be programmed with a string of characters (which may include control codes etc.) using a special function call. The defaul string for all keys is a null string.
Parameters : B @@FKEY (=8) (special function code)
C function key number (0..15)
DE pointer to string (length byte first)
Returns : A status
The maximum legth for each programmed string is 23 characters excluding
the length byte. An error (.KFSPC) will be returned if the
string is too long.
If the programmed string is of zero length (null string) then this
function key will cause a software interrupt when it is pressed. The
software interrupt code will be ?FKEY (10h) for
function key 0, up to ?FKEY+15 (1Fh) for
function key 15.
There is an EXOS variable called STOP_IRQ which controls
the action of the STOP key. If it is nonzero then the stop key
simply returns the ASCII CtrlC code (03h) in the same
way as all other keys. If STOP_IRQ is zero then instead of
this a software interrupt is caused, with software interrupt code
?STOP (20h).
When the HOLD key is pressed the keyboard driver hangs up
in its interrupt routine until the HOLD key is pressed
again. This will thus freeze any listing etc. which is being produced.
When it hangs up it calls a routine in the sound driver to silence the
DAVE chip since any sounds will be frozen.
When the HOLD key is pressed it displays the message
"HOLD" in place of the current lock mode on the status line.
This message will be replaced by the correct lock mode message (which is
blank for normal mode) when the hold is released. If the STOP key is
pressed while in hold mode then this will force an exit from hold mode,
and will then respond to the STOP key in the normal way.
While in hold mode the internal EXOS clock will still be updated so it will not loose time.
When a normal key is pressed the character code for it is simply put in
the buffer. However if the EXOS variable KEY_IRQ is
nonzero then as well as returning the character code, a software
interrupt will be caused with software interrupt code ?KEY
(21h).
A special function call is provided which will directly read the joystick on the main keyboard, or one of the two external joysticks on the control ports. The parameters for this call are:
Parameters : B @@JOY (=9) (special function code)
C 0 : internal joystick
1 or 2 : externnal joystick 1 or 2
DE pointer to string (length byte first)
Returns : A status
C b0 - set if right active
b1 - set if left active
b2 - set if down active
b3 - set if up active
b4 - set if fire active
b5..b6 - clear
Note that for the internal joystick the fire button is in fact the space bar.