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On the ST
from the keyboard. The normal method is to use the GEM
DOS console device. You can, however, communicate di
rectly with the keyboard itself. That's because on the ST, the
keyboard isn't just a dumb, passive hardware device. It's a
separate controller, with its own microprocessor, memory,
and I/O port. This level of sophistication allows the controller
to be used for tasks other than just fetching keystrokes. The
ST Intelligent Keyboard device (IKBD) is responsible for
tracking input from the mouse and joysticks, and it main
tains a time-of-day clock with one-second accuracy.
Keyboard Functions
The IKBD sends the ST a keycode each time a key is pressed
or released. A one-byte code is sent when the key is pressed
(make), which is the same as the first byte of the extended
keyboard codes shown in Appendix J. The one-byte code
that is sent when the key is released (break) is the same as
the make code plus 128. Thus, if the a key has an extended
code of $1E61, the make code sent by the IKBD when the a is
pressed is $1E, and the break code sent when it is released is
$9E.
Although there are 128 possible make codes, and 128
break codes, the ST does not use all of these codes for keys.
Codes $74 and $75 are sometimes used to translate mouse
button presses into keycodes. Codes $F6 through $FF are
used for the packet headers which signal that the next few
bytes of information will not be keycodes, but rather will
contain information about the mouse, joystick, clock, or
IKBD status. These packet headers are:
9 there are two ways of receiving input
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