HP-19C/-29C

The HP-19C included a small thermal printer, one of the very few hand-held scientific calculators to offer such a feature (HP-91, HP-92 and HP-97 were desktop units and later models like the HP-41C only supported external printers).

All other capabilities were the same in both models – RPN expression logic, 98 program memory locations, statistical functions, and 30 registers.

Users could develop software for the HP-29C/19C, such as a prime number generator.

[1] The calculators expanded the HP-25's program capabilities by adding subroutines, increment/decrement looping, relative branching and indirect addressing (via register 0 as index).

A version adapted to support an additional backward-facing display manufactured by Educational Calculator Devices named EduCALC 29C GD existed as well.