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QUSURE BA II Plus

Date of introduction:  2018 Display technology:  LCD dot matrix
New price:   Display size:  3 alpha + 10 (7+2)
Size:  6.0" x 3.0" x 0.6"
 153 x 76 x 15 mm³
   
Weight:  2.8 ounces, 79 grams Serial No:  
Batteries:  CR2032 Date of manufacture:  mth 03 year 2019
AC-Adapter:   Origin of manufacture:  China
Precision:  13 Integrated circuits:  ELAN EQ3804
Logic:  AOS Displays:  
Memories:  10    
Program steps:   Courtesy of:  Joerg Woerner

This Qusure BA II Plus caught our attention when we observed an uptick of "too good to be true" offers of the BA II Plus on eBay and they had two things in common:

2015-style of the calculator packaging
Original UPC barcode label taped over

We decided to acquire some of these suspicious calculators (around $15 to $20 per unit instead of the usual "street price" of $30 to $35) and share our findings how to authenticate a BA II Plus.

Here at the Datamath Calculator Museum we identified four different methods to identify a "fake" BA II Plus:

Packaging Labels - Only if original calculator packaging is available
Calculator Forensics - Can be performed without removing the calculator from its packaging
Look and Feel - Not destructive
Complete Teardown - Potentially destructive

Packaging Labels: We noticed on our quest to learn more about "fake" BA II Plus calculators that all of them had the original UPC label on the backside of their blister packaging taped over. Some had one label on top of the printed UPC label, others had two labels applied over the original label. UPC, short for Universal Product Code, is a barcode symbology used worldwide for tracking goods in stores. The Texas Instruments BA II Plus has the number 033317071784 assigned, clearly indicating it's authenticity. We think that the additional labels are meant to differentiate the "fake" calculators from the real ones but we have no proof for our assumption.


Calculator Forensics: Calculator forensics is a term coined by Mike Sebastian which seeks to answer the questions of who originally designed a particular calculator's chip set, what features of a particular calculator have been borrowed from earlier designs, and how has calculator technology spread among the manufacturer.

The evaluation algorithm chosen by Mike Sebastian and used in the Datamath Calculator Museum is (with the calculator in degrees mode and display format set to 9 digits after the decimal point):

arcsin(arccos(arctan(tan(cos(sin (9))))))

The keystroke sequence for the BA II Plus with its [2ND] and [INV] keys is: [9], [2ND][sin], [2ND][cos], [2ND][tan], [INV][2ND][tan], [INV][2ND][cos], [INV][2ND][sin]. This algorithm usually produces different results on different calculator models based on the accuracy of the algorithm used to implement its transcendental functions (otherwise it would have no value as an evaluation and comparison tool).

An authentic Texas Instruments BA II Plus manufactured after 2004 will display 8.999999994 - impressive close to the perfect result of 9.000000000. The BA II Plus uses internally 13 digits for its calculations but displays only a maximum of 10 digits. The so-called "Guarding Digits" can be revealed by a simple multiplication and subtraction directly followed the above sequence: [x], [1][0][0][0][0][0], [=], [-], [8][9][9][9][9][9], [=] for a result of 0.9993942. Stitching the two results together gives the 13-digit Calculator forensics result of an authentic BA II Plus with 8.999999993942.

The featured Qusure BA II Plus returns a display result of 9.000002051 and a 13-digit Calculator forensics result of 9.000002051244 - significantly different from current TI's BA II Plus calculators and even less accurate than the original BA II Plus introduced in 1991:

Calculator Forensics Result
BA II PLUS (1991) 8.999999883164
BA II Plus (2015) 8.999999993942
Qusure BA II Plus 9.000002051244

The Calculator forensics result of the Qusure BA II Plus looks familiar to as, both the Fiamo ABA10 Advanced Financial Calculator, a street-legal alternative of the BA II Plus, and the Radio Shack Model 65-115 Scientific Calculator report the same numbers.

Look and Feel: At first glance the Qusure BA II Plus and a Texas Instruments BA II Plus look identical, but the backside of the calculators show some differences:

The texture of the housing is different
The position of the reset label next to the reset button is offset
The font used for the date code is different

Complete Teardown: Disassembling the featured Qusure BA II Plus with Date code L-0516A and hence pretending to be manufactured in May 2016 by Kinpo Electronics, Inc. in the Philippines reveals an internal construction similar but not identical to a Texas Instruments BA II Plus with Date code L-1015A. Both products are centered around a single-chip calculator circuit mounted in Chip-on-Board (COB) technology directly on a double-sided printed circuit board (PCB) and powered by a CR2032 battery.

Removing the small blob of epoxy resin protecting the chip of the Qusure BA II Plus calculator reveals a microcontroller marked with EQ3804 and manufactured by ELAN Microelectronics Corporation, a semiconductor company headquartered in Hsinchu, Taiwan. Die size approximately 110 mils * 70 mils / 2.8 mm * 1.8 mm. Die Photo courtesy of Sean Riddle.

Inspecting the PCB of this Qusure BA II Plus calculator brought our attention to a small mark reading JC-V1.0, a possible hint to the designer and/or manufacturer of the calculator but definitely different from Kinpo's BF16-10-2 marking of an authentic BA II Plus manufactured in the same timeframe.

We disassembled the featured Qusure BA II Plus and an authentic BA II Plus manufactured in October 2015 completely to inspect their PCBs, keyboard contacts, LC-Displays and injection molded housing parts. While the printed circuit boards (PCBs) of the two calculator have the same shape and dimensions, are their electronic components and layout completely different.

The injected molded housing parts found in the salvaged Qusure BA II Plus are near-perfect copies of the authentic parts but some magic happens here! It is common practice for mold makers to include "date inserts" in the tool, an efficient way to mark when parts were molded for traceability and quality control. The sales box of the featured Qusure BA II Plus is suggesting a manufacturing date between 2015 (© of the box) and 2018 (change of TI's packaging design) and the calculator itself bears a date code suggesting May 2016. The two housing parts of this time traveller on the other hand were manufactured in January and February 2019.

The hypothesis suggested with the Calculator forensic results that the Qusure BA II Plus is a hybrid of the mechanical design of a Texas Instruments BA II Plus and the electronics of a Fiamo ABA 10 doesn't hold, the differences in the connection of the LC-Displays to the single-chip calculator circuits are valid counterevidence. The Qusure BA II Plus uses 38 contact pads for the display while the Fiamo ABA 10 uses 36 contact pads, suggesting a different mapping of the segments and pixels to the calculator brain.

Value of Authentic Products: Here at the Datamath Calculator Museum we won't answer the question if you should buy a fake TI BA II Plus calculator, but you should consider:

Functionality Issues - Calculation errors may be caused by fake calculators with their different embedded math algorithms
Build Quality - For the most part fake calculators have poor construction from lower-grade materials and less durable build
Reliability Concerns - Fake calculators may malfunction or may stop working totally after some time of their usage
Lack of Support - In comparison to original TI calculators, fake calculators don't have manufacturer support or warranty coverage
Ethical Considerations - Think about intellectual property rights and the issues about illicit trade practices



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

© Joerg Woerner, February 23, 2025. No reprints without written permission.