Texas Instruments TI-108

While screening in March 2024 the North American eBay website for Texas Instruments calculators, this TI-108 caught our attention. You could literally find hundreds of TI-108's during that day but this unit sports with P-1111H an unexpected Date code. And it is not about the numbers, "1111" simply translates into a manufacturing date of the 11^th month (November) of the year 2011. The unexpected characters are the leading "P" indicating as manufacturing place the Inventec Pudong campus in Shanghai, China, better known at the Datamath Calculator Museum for high tech products like the TI-Nspire CX or medium tech products like the TI-84 PLUS Silver Edition. The trailing "H" on the other hand indicates a product revision level H, meaning the design went through eight different iterations, not what you would expect from a low tech product like the TI-108 introduced already in 1986.

Dismantling the featured TI-108 manufactured in November 2011 reveals a pretty simple internal construction based on technology from the Nineties and very similar to a TI-108 manufactured in 2004 by Inventec in their original Shanghai facility. Main difference is the assembling technology of the single-chip calculator circuit. While the earlier model uses a traditional 28-pin package for the Sharp LI3154 chip, uses the later design the so-called Chip-on-Board (COB) technology where the Integrated Circuit (IC) is directly bonded onto a double-sided printed circuit board (PCB) and hidden under a small epoxy blob.

Inventec even kept the unusual place for the small backup battery, then a novel feature of the TI-108 hidden under the connecting cable of the LC-Display.

Inspecting the PCB of this TI-108 calculator brought our attention to a small mark reading TI108_KC8731, obviously a reference to its product name. We started compiling a list of the PCB-Marks on calculators manufactured by OEMs for Texas Instruments.

Production of the TI-108 was shifted in 2014 to Kinpo Electronics in China and the 3V Lithium battery replaced by a more common (and more economical) Alkaline button cell with 1.5V. Since 2016 - thirty years after its introduction, the TI-108 is manufactured in the Philippines.

Please find a detailed overview of the different hardware versions of the TI-108 calculators between 1988 and 2016 here.

Stokes Publishing Company, Inc. based in Sunnyvale, California sold a companion for the teacher, view the Basic.

If you have additions to the above article please email: joerg@datamath.org.

© Joerg Woerner, April 5, 2024. No reprints without written permission.