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Texas Instruments TI-30Xa (2013)

Date of introduction:  July 2013 Display technology:  LCD
New price:  $10.99 (SRP 2013) Display size:  10 + 2
Size:  6.0" x 3.0" x 0.6"
 153 x 76 x 15 mm³
   
Weight:  2.8 ounces, 78 grams Serial No:  
Batteries:  2*LR44 Date of manufacture:  mth 03 year 2013 (K)
AC-Adapter:   Origin of manufacture:  China (K)
Precision:  12 Integrated circuits:  
Memories:  3    
Program steps:   Courtesy of:  Joerg Woerner 

What a surprise, Texas Instruments changed in July 2013 the design of the original TI-30Xa - introduced already in 1996 - dramatically. The original design was used for five different calculators:

• TI-30Xa - replaced in 2013 with this new design
• TI-30Xa Solar - discontinued in most markets
• TI-36X Solar - replaced in 2004 with a newly designed TI-36X Solar
• BA Real Estate - discontinued long time ago
• BA-35 Solar - discontinued long time ago
 

In Europe a solar powered version of the TI-30Xa is sold as TI-30 ECO RS, it was upgraded to the new design line, too.

Disassembling this TI-30Xa manufactured in March 2013 by Kinpo Electronics, Inc. in China reveals no surprises. The printed circuit board (PCB) of the calculators sports still a prominent SR-30 logo - with a revision index of 12. A TI-30XA calculator manufactured four years earlier by Kinpo Electronics, Inc. carried the same SR-30-12 designator.

Since its introduction in 1996 we verify with each TI-30Xa the presence of the Logarithm Bug and - yes....

The algorithm problem known as "Logarithm Bug" was implemented already 1991 with the TI-35X and TI-36X SOLAR and floats around in various calculators.
The best way to demonstrate the logarithm bug could be found with the exponential function, one of the most important functions in mathematics. It is written as ex and can be defined as a limit of a sequence:

The calculation of this expression will yield to unexpected results due to:

• The ln(1 + x) problem 
• The way yx is calculated

Using n=109 should reveal a very close approximation of ex=2.71828183 (rounded to 9 digits) but this TI-30Xa manufactured in 2013 still indicates 2.71919279. Ready for a surprise? Texas Instruments fixed the logarithm bug in 2015 - don't miss the revised TI-30XA



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

© Joerg Woerner, August 12, 2013. No reprints without written permission.