Texas Instruments TI-82 (Engineering Sample)

Date of introduction:  (August 1993 Display technology:  LCD dot matrix
New price:   Display size:  8 * 16 characters
Size:  6.8" x 3.1" x 0.85"    
Weight:  5.6 ounces Serial No:  
Batteries:  4*AAA + CR1620 (35mA) Date of manufacture:  mth 06 year 1993
AC-Adapter:   Origin of manufacture:  Taiwan (I)
Precision:  14 Integrated circuits:  CPU: Toshiba T84C00
 ASIC: Toshiba TC14L010
 ROM: TC541001AF
 RAM: SRM20256
 Display: Toshiba T6A04
Program steps:  28k Bytes Courtesy of:  Joerg Woerner

TI-82_ES_PCB.jpg (396422 Byte)TI-82_ES_Back.jpg (242671 Byte)This TI-82 was manufactured in or around June 1993 and seems to be a very early engineering sample. Dismantling the calculator - lacking both serial number and date code - reveals a little surprise. Instead of the Sharp LH531 Mask ROM found in later products, a Toshiba TC541001AF OTP ROM (One Time Programmable ROM) uses its real estate on the printed circuit board (PCB).

TI-82_ES_PCBM.jpg (230771 Byte)Mask ROM, as the name suggests, refer to a kind of ROM (Read Only Memory) whose contents are programmed by the chip manufacturer. Main advantage of Mask ROM is its cost per component, while main disadvantages are both long lead times and the high costs of design errors. It was in the late 80s and the 90s common practice to use rather expensive user-programmable memories, for instance OTP ROM, till the software has finalized. (We know about 12 different ROM-Versions of the TI-82...).

TI-82_ES_LCD.jpg (146766 Byte)Everything else is identical with the later TI-82 sporting the LH531 Mask ROM, even the Toshiba T6A04 driver circuit of the LC-Display was used in the design. Learn more about the Hardware Architecture of TIís Graphing Calculators.


TI-82_ES_OS.jpg (43895 Byte)3*


You can check the ROM version of your TI-82 using the following key sequence and reading the number on your screen:


Information provided by and Xavier Andrťani.

Exam acceptance:

The TI-82 is permitted (as of September 27, 2007) for use on SAT, ACT, PSAT and AP exams.


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© Joerg Woerner, February 6, 2009. No reprints without written permission.