HP 11C

The HP 11C is a midrange scientific calculator from the HP Voyager series.

HP 11C

Type	Scientific
Introduced	1981
Discontinued	1989
Predecessor	HP 33, HP 34C
Calculator
Entry mode	RPN
Display type	Segmented LCD
CPU
Processor	HP 1LE3, 1LF5, 1LM2, 1LQ9
Frequency	200-230KHz
Programming
Other
Power supply	3x SR44/LR44/AG13

Features

Introduced in 1981, the HP 11C was the first HP Voyager model released to the market. The HP 11C is placed between the HP 10C and HP 15C in terms of features offered. Consequently, a large portion of the units manufactured use the earliest Voyager internal designs, as after the introduction of the HP 15C in 1982 popularity of the 11C fell sharply.

Hardware revisions

The earliest 11C revisions used two separate PCBs, one with the logic and display, and a second with the keypad. Later revisions consolidated everything down to one board further reducing cost.

Electrostatic discharge (ESD) protection was a major consideration in the design of early voyager models, as time went on the methods of ESD protection on the 11C changed. Early models had minimal protection, one spring to connect the front and back metal plates, and conductive textured rubber feet connected to the rear metal plate with a copper tab. Later models switched to two springs and omitted the copper tab and conductive feet, while adding additional plastic sheets on the rear of the button PCB.

Date code	Battery contact type	Processor	PCBs	ESD shielding	Springs	Grounded feet
2127	Metal tab	1LE3	2	Minimal	1	Yes
2137	Metal tab	1LE3	2	Large plastic flaps	1	No