unit INKEY:function:integer;
This function checks for pressed key but
is not waiting for an input. The key
code is returned if the key was pressed and 0 if
not. Special keys return the following codes:
F1 = -10 F9 = -18 Right = -26
F2 = -11 F10 = -19 Up = -27
F3 = -12 Insert = -20 Down = -28
F4 = -13 Home = -21 Tab = 9
F5 = -14 End = -22 Esc = 27
F6 = -15 PgUp = -23 Backspace = 8
F7 = -16 PgDown = -24 Del = 117
F8 = -17 Left = -25