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Texas Instruments TI-30XA

Date of introduction:  April 2004 Display technology:  LCD
New price:  $10.99 (SRP 2008) 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 06 year 2007 (E)
AC-Adapter:   Origin of manufacture:  China (S)
Precision:  12 Integrated circuits:  
Memories:  3    
Program steps:   Courtesy of:  Joerg Woerner 

TI-30XA_S0607_1.jpg (339563 Byte)TI-30XA_S0607_Back.jpg (136970 Byte)This TI-30XA manufactured in June 2007 is almost identical with the TI-30Xa introduced already in 1996 and slightly redesigned April 2004. We purchased this particular calculator in Canada to verify if the Logarithm Bug is still present in the calculator chip.

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

TI-30XA_S0607_Bug.jpg (85276 Byte)Using n=109 should reveal a very close approximation of ex=2.71828183 (rounded to 9 digits) but this TI-30XA manufactured in 2007 still indicates 2.71919279.

TI-30XA_S0607_PCB.jpg (244127 Byte)Dismantling the latest TI-30XA is somewhat boring, we noticed a printed circuit board (PCB) known already from the previous models. 

In 2009 the long lasting TI-30XA was revised and received a display with larger display. Don't miss the upgraded TI-30XA.



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

Joerg Woerner, November 10, 2007. No reprints without written permission.