I get interesting results using: ?6\n1500 13 0 25\nY\n
At least, didn't crash in my tests, average 20s/m in middlegame/early endgame on my i5.
According to this quote from Awit-2009-ReadMe.txt, it looks like the maximum acceptable setting :
Code:
The 0 0 0 0 defaults were suitable for INTERMEDIATE, TOURNAMENT and
EXPERIMENTAL modes. The maximum width of search was 19 moves (but has now
been increased to 25). Originally MAXTREE was limited to 999 nodes, but has
now been increased to 9999, providing greater flexibility and variety in the
three advanced modes of play. This change was made to take some advantage of
the greater speeds of today's computers, but no serious testing has been done
with values of MAXTREE greater than 1500.
MfG,
Eric