ACT apricot - Page 271

KEYBOARD DRIVER
STOP If the keyboard is in the STOP mode, then this
is released and the stop LED is extinguished,
otherwise the stop LED is illuminated, and the
STOP mode is asserted.
CALC
If the calculator is OFF, a "wake-up" signal is
sent to the internal BIOS calculator which then
sets up the MicroScreen display (saving the
original contents) and sets the CALCULATOR
ON flag. If the key is pressed when the
calculator is on, a RESET signal is sent to the
internal calculator, which then re-initialises
itself.
For
normal or string keys, the routine then checks
whether the keyboard is in the STOP mode, if it is, then the
STOP mode is released, and the STOP key LED is
extinguished.
This means that apy key depression (exept for
a 'special' key)
can be used to release the STOP mode.
The key number is placed in a 16- byte down-buffer where
it is held un til the key is released, if the buffer is full then
the number is simply forgotten - in either case, the count of
keys
held down is incremented by 1.
If the number of keys held down is one, then the
AUTO-REPEAT lead-in delay count is initialised.
The CALCULATOR ON flag is then checked to see if we
are in the CALCULATOR MODE. If so, then the key is
checked via a special bit-map to see whether it should be
sent to the calculator module, if it is, then the key number
(raw down-code minus 1) is sent to the calculator module.
The module performs all error checking, MICROSCREEN
output etc.
The key is then checked for "local" type - if it is then the
internal destination flag is set to screen output, rather than
MS-DOS output.
The prefix-bits of the key type are then checked and the
appropriate ESC prefix (ESC, ESC [ or ESC 0) codes are sent
to the output queue.