Apple Lisa - Mouse Data

Confidential
Lisa Hardware Reference Manual
MOUSE DATA
Mouse generated data is sent to the 68000 in three bytes:
00
dx
dy
(mouse
data follows)
(change in X direction)
(change in Y direction)
The dx and dy values, which are in the range of -128 to 127, are
reset every time the 68000 reads them. While the mouse is moving
and mouse
interrupts are enabled, a new dx and dy value can be
read every nnn*4 ms. If the 68000 does not respond to the mouse
interrupt and read the mouse data, the dx and dy values are updated
and collected in the interface's eight byte FIFO buffer. If the
mouse is ignored long enough, the buffer will overflow, and mouse
data will become invalid.
The mouse button is returned as keycode dOOO 0110. If the d bit is
1, the button has been pressed, and if the d bit is 0, the button has
been
let up. The d bit in the keycode dOOO 0101 is 1 if the mouse is
plugged in, and a if it is not. The third mouse "keycode" (dOOO
0111) is currently unused.
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7-Jul-81~