pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-2740-tunes.ps) >>/Users/jc/w/tmp/Tune-2740-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/book/DftY/1767/Thompson/tunes.abc

Error exit status 256; here are some files to check:
[get.cgi V=1/1 B=0 scale=0.55 512x512 PNG]
filesizedescription
Coll_27402.log 285735 Log file, useful mostly for debugging
Coll_27408.log 294165 Log file, useful mostly for debugging
Tune-2740-get.log 17433 Log file, useful mostly for debugging
Tune-2740-tunes.abc 21357 ABC music file with the extracted tune(s)
Tune-2740-tunes.ps 124743 PostScript
Tune-2740-tunes.txt 21357 Plain-text file with the extracted tune(s)
Tune-27403-get.log 3747 Log file, useful mostly for debugging
These files should be available for 24 hours.