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Texas Instruments TI-30XA (2009)

Date of introduction:  January 2009 Display technology:  LCD
New price:  $10.99 (SRP 2009) Display size:  10 + 2
Size:  5.9" x 3.0" x 0.50"
 150 x 75 x 13 mm3
   
Weight:  2.9 ounces, 82 grams Serial No:  
Batteries:  2*LR44 Date of manufacture:  mth 01 year 2009 (F)
AC-Adapter:   Origin of manufacture:  China (K)
Precision:  12 Integrated circuits:  
Memories:  3    
Program steps:   Courtesy of:  Joerg Woerner 

Texas Instruments released rather silent in January 2009 the TI-30XA with larger digits and even in September 2009 most stores in Upstate New York carry a mix of "old" and "new" calculators in their shelves. The only visible difference for the customer is a small sticker "New Larger Digits!" on the sales box.

In Europe a solar powered version of the TI-30XA is sold as TI-30 ECO RS, it was upgraded to the larger digits, too.

A first inspection of the revised TI-30XA confirms indeed a nice display with bold, huge digits and even without placing two calculators side-by-side we recognized the improvement immediately.

Disassembling this TI-30XA manufactured in January 2009 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 five years earlier by Kinpo Electronics, Inc. carried e.g. the SR-30-10 designator.

In 2013 Texas Instruments introduced again a TI-30Xa - using identical electronics in a newly designed housing.

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 2009 still indicates 2.71919279.



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

Joerg Woerner, November 16, 2009. No reprints without written permission.