DATAMATH CALCULATOR MUSEUM
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DATAMATH CALCULATOR MUSEUM |
Texas Instruments TI-81
| Date of introduction: | March 1991 | 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 |
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| Weight: | 5.8 ounces, 172 grams | Serial No: | 0917651 |
| Batteries: | 4*AAA | Date of manufacture: | mth 09 year 1991 |
| AC-Adapter: | Origin of manufacture: | Taiwan (I) | |
| Precision: | 13 | Integrated circuits: | CPU: Toshiba T6A43 ROM: ©1991 RAM: LH5160 Display: 2*Toshiba T7778A, T7900 |
| Memories: | 0-27 | ||
| Program steps: | 2400 Bytes | Courtesy of: | Joerg Woerner |
We
recently acquired this unique TI-81 manufactured in September 1991 and discovered
some interesting features:
The calculator still lacks a backup battery but sports on the
backside of the sales package the "Constant Memory™" feature. Please
remember: The TI-81, like all Texas
Instruments graphing calculators including even the latest TI-84 Plus
Silver Edition,
store the user program, user data and even calculator and display settings in a
volatile C-MOS memory. To avoid the lost of the memory while replacing the main
batteries, the mentioned calculators use an additional, coin-shaped, backup
battery. Please read the warning in the 1st edition of the TI-81
Graphics Calculator Guidebook.
Dismantling this TI-81 manufactured in Fall 1991 reveals the
next surprise. We expected - based on the experience from an earlier TI-81
manufactured in Fall 1990 and the rare TI-81 Engineering
Sample - the Toshiba T6A49A Application Specific CPU. Instead we discovered
the proven T6A43 from the PS-6600
Organizer, used in the more common TI-81 version with
backup battery. Learn more about the
Hardware Architecture of TI’s Graphing Calculators.
Comparing the display boards of different TI-81 models reveals
almost identical printed circuit boards (PCBs) populated with either the Toshiba
T7778A column drivers and T7900 row drivers or the probably identical T6A39 and T6A40
chips.
Early in 1992 the internal construction of the TI-81
was revised and missing backup battery was added. Please find a detailed
overview of the different hardware architectures of the TI-81 generations
between 1990 and 1995 here.
Fellow collectors - if you own a TI-81 w/o backup
battery please report us the serial number and date code
from the back of the calculator plus the ROM-Version for our TI-81 1st
gen Database.
Don't miss a rare TI-81 Engineering Sample, manufactured probably in April 1990.
ROM-Versions:
1.6K
You can check the ROM version of your TI-81 using the following key sequence and reading the number on your screen:
