Hewlett-Packard HP-42S RPN Scientific Calculator released in 1987.

Hewlett Packard HP 42S RPN Scientific Calculator Vintage 1987 w/ Battery Tested

Vintage HP-42S RPN Scientific Calculator w/ Original Case

HP 42S HP-42S RPN Scientific Calculator w Original Box Manual Case NICE

Vintage HP-42S RPN Scientific Calculator w/ Original Case & Manual WORKS!

Hewlett Packard HP 42S RPN Scientific Calculator w Astech Hard Case

Hewlett-Packard HP-42s RPN Calculator Owner's Manual, Spiral Bound

HP-42S RPN Scientific Calculator with Case - Tested Working