Don't recall just when it came out but - Biggest problem with it was finding someone to have a QSO with. Once you did the link was very good. I think it was also used by a lot of the early BBS stations. Of course that was the problem with any ARQ mode that came along. Back in 1977 or so when you friend Alen come along with AMTOR that really was the 1st widely used ARQ mode. Very few could part with the $300 U.S. dollars for the kit. Sitting over in a cord board box in the storage area is AMTOR kit # 314.
I recall at the time having never worked so many G stations the entire time that I had been a ham. And as they say the rest is history. John, W0JAB