HP Pioneer series calculator internals
Nov. 17. 2009
Japanese edition is here.
PCB of the HP pioneer series calculators
Left: HP-17BII, Center: HP-27S, Right: HP-42S(modified)
Key pad and back plate (with LCD)
Partial schematic of the HP 17BII/27S/42S
HP 42S memory upgrade and overclock
Pioneer "Observational Internals", Paul J. Brogger
Copyright (c) HOSODA Takayuki. All rights reserved.