If I recall, Ymodem-G (as opposed to Ymodem) was basically an unchecksummed raw file dump with a little metadata header, so it was only usable on a connection w

If I recall, Ymodem-G (as opposed to Ymodem) was basically an unchecksummed raw file dump with a little metadata header, so it was only usable on a connection without line noise. You could actually get undetected file corruption.