Got HTTP status 404 Not Found for "http://john-chambers.us/~jc/music/book/1776/proto.abc"
pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-3064-proto.ps) >>/Users/jc/w/tmp/Tune-3064-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/book/1776/proto.abc

Error exit status 256; here are some files to check:
[P=tuneget V=1/1 B=0 scale=0.70 512x512 PNG]
filesizedescription
Coll_30645.log 279212 Log file, useful mostly for debugging
Tune-3064-AMHSI_abc2.abc 147 ABC music file with the extracted tune(s)
Tune-3064-AMHSI_abc2.txt 147 Plain-text file with the extracted tune(s)
Tune-3064-get.log 7133 Log file, useful mostly for debugging
Tune-3064-proto.abc 142 ABC music file with the extracted tune(s)
Tune-3064-proto.ps 6 PostScript
Tune-3064-proto.txt 142 Plain-text file with the extracted tune(s)
Tune-30641-get.log 1446 Log file, useful mostly for debugging
These files should be available for 24 hours.