ACT apricot - Page 273

KEYBOARD DRIVER
4. Translation of data routines
These routines use the keyboard lookup tables to
establish the data and attributes of a key.
5. Auto Repeat handler
The auto repeat handler is called by the timer interrupt
routine every 20ms, the routine first checks to see if the
number of keys down is one - if not it aborts.
If the count is 1 then the clock rate is divided to give the
basic auto repeat period (e.g. lOcps = lOOms per char - 5
20ms periods).
If an auto-repeat rate period has been reached, then the
current mode is checked to see if the keyboard is in the
STOP mode - if so then the routine does not repeat.
The lead-in delay count is then decremented, if it is not
zero then the routine aborts, otherwise an "auto-repeat"
operation is performed:
The CALCULATOR ON flag is checked - if the
calculator is on, or the key is a special key then no auto
repeat is done.
If all is okay, the previous key sequence is repeated, then
the Auto Repeat module is re-entered. This continues until
the key is released (up-code).
6~ Non make/break code interpreter
This part of the keyboard software is used as a junction for
other keyboard-related operations such as dateltime, mouse
codes and Mscreen feedback. In each case control is passed
to the relevant device driver.