pscmd="(jcabc2ps /Users/jc/w/tmp/Tune-22794-BostonCollection.abc -F fmt/pdf_60.fmt +s 0.60 +maxs 2000 )>/Users/jc/w/tmp/Tune-22794-BostonCollection.ps 2>>/Users/jc/w/tmp/Tune-22794-get.log" returned status 34304.
pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-22794-BostonCollection.ps) >>/Users/jc/w/tmp/Tune-22794-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/book/BostonCollection/BostonCollection.abc

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-22794-BostonCollection.abc 9432 ABC music file with the extracted tune(s)
Tune-22794-BostonCollection.ps 61344 PostScript
Tune-22794-BostonCollection.txt 9432 Plain-text file with the extracted tune(s)
Tune-22794-get.log 55802 Log file, useful mostly for debugging
These files should be available for 24 hours.