pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-34920-slip.ps) >>/Users/jc/w/tmp/Tune-34920-get.log 2>&1" returned status 256
http://abc.sourceforge.net/NMD/nmd/slip.txt

Error exit status 256; here are some files to check:
[P=get.cgi V=1/1 B=0 scale=0.60 512x512 PNG]
filesizedescription
Tune-34920-get.log 7299 Log file, useful mostly for debugging
Tune-34920-slip.abc 226 ABC music file with the extracted tune(s)
Tune-34920-slip.ps 34017 PostScript
Tune-34920-slip.txt 226 Plain-text file with the extracted tune(s)
These files should be available for 24 hours.