With 128MB of RAM, s1945p will take some time (around 10 minutes) to
decrypt the graphics ROMs, but once that is done it should play fine,
but it should be noted that it is rather jerky at times (fault of the
emulation) rather than a constant slowdown as the arcade verson would
do (although I've never actually played the arcade version).
<p>
Another option would be to use Kawaks which not only seems to run
s1945p a bit better than MAME, but also has an option to save the
decrypted graphics ROMs, so that you avoid the long loading time on
128MB of RAM. Upgrading to 256MB of RAM will certainly speed up the
decryption process greatly (should only take a few seconds).
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bsr@hnpl.net