HP-19C

The HP-19C was functionally equivalent to the HP-29C with the addition of a built-in printer and a keyboard buffer. Unlike, the HP-67, the HP-29C did not provide "printing" commands in order to be completely program compatible with the HP-19C. This degree of interoperability wasn't required since programs couldn't be transported from an HP-19C to an HP-29C on magnetic cards. Users could simply add or delete printing commands as the program was entered. In fact HP's applications books were written for the HP-29C and had "***" in places where an HP-19C owner might want to insert a print instruction.