HP Pioneer series

The HP Pioneer series is a line of calculators produced by HP between 1988 and 2003.

Construction

As a cost reducing measure, all models use the same molded textured two-part plastic chasis and the same IR-transparent battery cover. The battery cover is attached to the rear piece, and eight heat stakes are melted and expanded, creating a solid bound. The top four heat stakes are under the battery cover while the bottom four are covered by the A single metal piece keyboard overlay/front bezel is painted with each product's designation and has keyboard legend printed on them, which is then glued to the calculator.

Internally, the rear part houses a piezoelectric beeper (17B/BII, 27S, 42S), and a metallic RF shield (for earlier models). The LCD and keyboard backing forms a single piece, heat-staked to the front of the machine with 46+2 heat stakes, and six metallic prongs from this layer are twisted after inserting into the PCB to create pressure that create contact between the PCB and contact points on the PCB. The keyboard contacts are on a flexible layer that is pressure onto the PCB with a single piece of foam. The PCB also has one spring contact on the frontside to contact the goundplane of keyboard and two on the backside to power the piezo beeper (if applicable).

The keyboard is formed from several layers. The topmost layer, the keys themselves are molded as blank keys to the front half of the chasis, and then machined and a different color plastic injected to form letters and symbols. Some later models manufactured switched to a paint process that is more subjected to wear. below that, three mylar layers, from top to bottom the "domed" carbon switch layer, the trace layer, and one clear layer that isolates the trace layer from the keyboard backing. Below those, one metal backing that also houses the LCD, and is where the heat stakes are staked to. Contrary to popular belief there is no metallic dome and the switch is purely membrane.

Features

Features of Pioneer series models

LCD Display	Model	Entry	Saturn core	Programming	Solver	Infrared
12-digit 7 Segments	HP 10B	Infix	Bert	No	No	No
	HP 20S	Infix	Bert	Yes (infix)	No	No
	HP 21S	Infix	Bert	Yes (infix)	No	No
12-digit 5x7 Dot Matrix	HP 14B	Infix	Sacajawea	No	No	No
	HP 22S	Infix	Sacajawea	No	Yes	No
	HP 32S	RPN	Sacajawea	Yes	Yes	No
	HP 32SII
131x16 Dot Matrix	HP 17B	Infix	Lewis	No	Yes	Yes
	HP 17BII	Infix/RPN
	HP 27S	Infix	Lewis	No	Yes	Yes
	HP 42S	RPN	Lewis	Yes	Yes	Yes

Note: Solver can be used to "program" some tasks, for example implementing trigonometry on the 17B series, or do numerical integration on the 27S series.