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Texas Instruments TI-30 ECO RS (2009)

Date of introduction: | January 2009 | Display technology: | LCD |

New price: | Display size: | 10 + 2 | |

Size: | 5.9" x 3.0" x 0.50" 150 x 75 x 13 mm ^{3} |
||

Weight: | 2.9 ounces, 82 grams | Serial No: | |

Batteries: | n.a. | Date of manufacture: | mth 04 year 2010 (K) |

AC-Adapter: | Origin of manufacture: | China (N) | |

Precision: | 12 | Integrated circuits: | |

Memories: | 3 | ||

Program steps: | Courtesy of: | Joerg Woerner |

Texas
Instruments released rather silent in January 2009 this
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. On a business trip to Germany in
2010 we found the related TI-30 ECO RS with the
larger digits, too.

A
first inspection of the revised TI-30 ECO RS 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-30 ECO RS manufactured in April 2010 by
Nam Tai Electronics,
Inc. in China reveals no surprises. The printed circuit board (PCB) of the
calculators looks very familiar to us and even the product name etched on it
confirms: TI-30XA SLR.

Since its introduction in 1996 we verify with each TI-30Xa
based calculator
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 e^{x} 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 |

Using
n=10^{9} should reveal a very close approximation of e^{x}=2.71828183
(rounded to 9 digits) but this TI-30 ECO RS manufactured in 2010 still indicates 2.71919279.

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

© Joerg Woerner, January 19, 2011. No reprints without written permission.