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Texas Instruments TI-81

Date of introduction:  October 1993 Display technology:  LCD dot matrix
New price:  $110 Display size:  8 * 16 characters
Size:  6.8" x 3.1" x 0.85"
 172 x 80 x 21 mm3
   
Weight:  5.6 ounces, 168 grams Serial No:  20023247
Batteries:  4*AAA + CR1620 Date of manufacture:  mth 08 year 1994 (F)
AC-Adapter:   Origin of manufacture:  Taiwan (I)
Precision:  13 Integrated circuits:  CPU: Toshiba T84C00
 ASIC: Toshiba TC14L010
 ROM: LH5359©1993
 RAM: SRM2264 
 Display: T6A04
Memories:  0-27    
Program steps:  2400 Bytes Courtesy of:  Joerg Woerner

TI-81_I0894F_Back.jpg (267776 Byte)Texas Instruments changed in 1993, together with the introduction of the TI-82, the design of the TI-81 slightly. Please notice the position of the TI-logo, it moved from the upper right position to the upper left of the screen.

From much higher interest to us are the design changes inside the third series of the TI-81. Dismantling this calculator manufactured in February 1994 reveals two major changes:

The three display drivers (two T6A39 column drivers and one T6A40 row drivers) housed in huge Quad-Flat-Pack packages of the original design were replaced by one tiny Toshiba T6A04 chip directly attached to the flexible printed circuit board (Flex-PCB) of the LCD display.

Even the main printed circuit board (PCB) was changed completely and looks identical to the PCB found in the TI-82. Instead the Toshiba T6A43 - an application specific Z80 controller - it accommodates now with the Toshiba T84C00 a standard Z80 CPU with an additional ASIC Toshiba TC14L010 (1.0 micron C-MOS gate array with 1,000 usable gates). 

We recently learned that the major changes in the hardware design are not correlated with the cosmetical changes. A fellow collector noticed identical hardware in a TI-81 sporting the old design and manufactured in September 1993.

Texas Instruments changed in 1995 the design of the TI-81, TI-82 and TI-85 slightly, please notice the position of the TI-logo and the color of the type designator. Please find a detailed overview of the different hardware architectures of the TI-81 generations between 1990 and 1995 here.

 

ROM-Versions:

2.0V

You can check the ROM version of your TI-81 using the following key sequence and reading the number on your screen:

[2nd] [TEST] [ALPHA] [S]

Information provided by ticalc.org and Xavier Andréani.

Exam acceptance:

The TI-81 is permitted (as of September 27, 2007) for use on SAT, ACT, PSAT and AP exams but is not recommended for the AP exam.  

 

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

© Joerg Woerner, December 5, 2001. No reprints without written permission.