The IBM Proprinter was a relabeled Epson MX-80, Bill. Reason I know this is because in 1984, I went into the computer lab at the college I was going to school at (Jefferson State Jr. College, Pinson, AL) and one of the printers was chiming a code that I instantly recognized as "paper jam". Fixed the jam in about eight seconds, only then looking at the label on the printer, which initially confused me. It was an IBM Proprinter... but it was, in reality, a rebranded MX-80. Possibly a MX-80+, but made by Epson all the same. (One reason I know this? Had to tear down a Proprinter once. It had the same innards as the Epson MX-80...). Those were not good days for me in too, too many ways.