I have a Rapidman 1208 LC desktop calculator, with an unusual rear illuminated LCD. It has a standard incandescent lamp that backlights a white on black LCD. It's just a little four banger as well.
Rockwell and Texas Instruments produced the earliest LSI calculator chip sets. Many companies purchased chipsets from Either Rockwell or TI, and did their own branded designs. HP did their own models, relying on their own designs (with some early mask development and production contracted to MOSTEK). MOSTEK focused on DRAM and second sourcing microprocessors, but ultimately failed against asian DRAMs. MOS Technologies (not MOSTEK) was also a major supplier of early calculator chipsets, as well as CPUs (like the MOS 6502). Unlike MOSTEK, MOS Tech was bought by Commodore, and became a MAJOR manufacturer that shifted towards computing to survive, after calculator prices dropped. There are actually a large variety of Commodore calculators that have some impressive feature sets, all based on MOS chips.
The keyboard on that Rapidman you were sent looks like one of the variants of the TI Klixon keyboard, just with smaller keycaps than is traditional. Companies could use whatever style keycap they wanted, as the Klixon was a self contained unit, more or less. Again, TI sold the part and other calculator manufacturers used it as an off the shelf component to manufacture their own models. Some companies even bought the TI keycap set (shown below) and just silkscreened whatever symbols they wanted. TI even sold the keycaps as a double shot injection molded variant! The fact that there are domes for the entire grid, even thought he entire grid isn't utilized is a solid indication that it's an off the shelf part, vs something made custom for that calc.
Hmm... Klixon keyboards... I think this is a legit one, but you never know! Maybe it's a knockoff! Does the PC board say a number followed by KS anywhere, like 1KS, or 6KS?
LOL, I can always use a Rapidman! XD
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