Hallicrafters came out with the T.T.O. Keyer "fully transistorized digital keyer" model HA-4. It was self completing. I think it was only produced for a year or two. The first year of production was 1961. It didn't sell well. The T.O. Keyer, HA-1 which was commonly paired with the vibroplex continued in production untill 1969. The T.T.O. is very rare.