HP 19C - Francis WEB

The HP 19C was introduced in 1975, and was using LED display. At the same time, Hewlett-Packard introduced several calculators, including the HP-10, HP-21, HP-22, HP-25, HP-25C, HP-27, HP-29C and the HP-19C.
The suffix C indicates that this calculator has Continuous memory. A very big advantage from the normal programmable calculators, because once you turn the power OFF you still keep the program amd registers. I owned an HP-25 around that time, and I remember having to type my program every time I switched the calculator ON.

The HP-19C and HP-29C were extremely similar, with the difference that the 29C did not have an internal printer. But all the functions, programming and use are identical.

The HP-19C is very compact, even with the internal printer:

The switch on the top left will set the calculator in program mode or run mode. The one on the right will set the behavior of the printer (either Manual, Trace or Normal).
Without going into all the technical details, we can see that we have all the scientific functions available, and 98 steps of programming.

This calculator, as all the other ones made by HP at that time, is using the Reverse Polish Notation (RPN) system to calculate. For those of you who are not familiar with it, instead of entering the operation like you see it on the paper, you are using registers.
Example:  34 + 45 = ?
- With a normal calculator you would type the number "34" then the "+" sign, then the number "45" and finally the "=" sign
- With RPN calculator you type: "34" then "ENTER" then "45" then "+"
By pressing the ENTER key, you move the first number to the next register. Then you type the second number, and you specify what to do with these 2 numbers.

I remember being confused the first time I used my HP-25, but this method was very useful for long calculations and is very easy to understand after praticing a little.

This is a favorite for collectors as the number of units for sale is very small. I only recorded 17 transactions during the past few years with an average price of $294.

If you see one, jump on it !