pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-96733-1774_Thompson.ps) >>/Users/jc/w/tmp/Tune-96733-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/book/dfty/1774_Thompson.abc

Error exit status 256; here are some files to check:
[P=tuneget V=1/1 B=0 scale=0.70 512x512 PNG]
filesizedescription
Tune-96733-1774_Thompson.abc 16966 ABC music file with the extracted tune(s)
Tune-96733-1774_Thompson.ps 130465 PostScript
Tune-96733-1774_Thompson.txt 16966 Plain-text file with the extracted tune(s)
Tune-96733-get.log 17070 Log file, useful mostly for debugging
These files should be available for 24 hours.