So I looked and there seem to be two board layouts involved here. The one's with the Intel flash seem to work fine. The others that have the MemoCom? flash don't work. The one's with MemoCom are missing several test points visible from the battery compartment as visible on the images on the webpage:

http://bb.osmocom.org/trac/wiki/MotorolaC140

So maybe there is something different about these other C140 that makes them not work with osmocon.

I get:

pi@raspberrypi ~/osmocom-bb/src/host/osmocon $ ./osmocon -d tr -p /dev/ttyUSB0 c140 ../../target/firmware/board/compal_e86/hello_world.compalram.bin
got 7 bytes from modem, data looks like: 66 74 6d 74 6f 6f 6c  ftmtool
Received FTMTOOL from phone, ramloader has aborted
got 1 bytes from modem, data looks like: 65  e
got 1 bytes from modem, data looks like: 72  r
got 1 bytes from modem, data looks like: 72  r
got 1 bytes from modem, data looks like: 6f  o
got 1 bytes from modem, data looks like: 72  r
got 1 bytes from modem, data looks like: 66  f
got 1 bytes from modem, data looks like: 74  t
got 1 bytes from modem, data looks like: 6d  m
got 1 bytes from modem, data looks like: 74  t
got 1 bytes from modem, data looks like: 6f  o
got 1 bytes from modem, data looks like: 6f  o
got 1 bytes from modem, data looks like: 6c  l