DATAMATH CALCULATOR MUSEUM
Texas Instruments TI-85
|Date of introduction:||1995||Display technology:||LCD dot matrix|
|New price:||$130||Display size:||8 * 21 characters|
|Size:||6.8" x 3.1" x 0.85"|
|Weight:||5.6 ounces||Serial No:||27074117|
|Batteries:||4*AAA + CR1620||Date of manufacture:||mth 03 year 1995 (G)|
|AC-Adapter:||Origin of manufacture:||Taiwan (I)|
|Precision:||14||Integrated circuits:|| CPU: Toshiba T6A43
Display: 2*T6A39, T6A40
|Program steps:||28k Bytes||Courtesy of:||Joerg Woerner|
Instruments changed in 1995 the design of the TI-81, TI-82 and
please notice the position of the TI-logo and the color of the type designator.
The featured calculator was manufactured in March 1995, two years before it was
discontinued in 1997.
Dismantling the TI-85 reveals only minor changes compared to a very early calculator manufactured already in October 1992: The connector of the serial port was moved slightly and the OTP-ROM ( One-time Programmable Read-Only Memory) replaced with a Mask-ROM.
makes still use of six main components on the printed circuit
CPU (Central processing Unit): The Toshiba T6A43 is a so-called Application Specific CPU and combines a Z80 core with an ASIC (Application Specific Integrated Circuit). You’ll find different approached within the graphing calculator line of Texas Instruments, sometimes the use of an individual CPU (e.g. Z80 and M68000) with a supporting ASIC or – like with this TI-85 - the integration of the CPU into the ASIC.
ROM (Read Only Memory): The ROM contains the operating system of the calculator. The first products on the market used mask-programmable ROM’s, the program was strored already during the production of the Integrated Circuit. Later calculators changed to Flash ROM’s, a technology allowing the programming of the software during the final production stage of the calculator. With the TI-83 Plus and all later graphing calculators from Texas Instruments even the user was able to reprogram the operating system.
of this TI-85 was manufactured by Sharp, Japan. Please notice the late Copyright
of the ROM, the TI-85 was introduced in 1992. We noticed in early TI-85
one-time programmable ROM TC541001
manufactured by Toshiba.
manufactured by Toshiba.
RAM (Random Access Memory): The RAM is used as data memory and is used to store both variables, user programs and intermediate results. This TI-85 makes use of SRM20256 manufactured by Suwa Seikosha, Japan. The capacity of the memory is 32k Bytes.
DISPLAY: The two Toshiba T6A39 are column drivers for small-to-medium-sized dot matrix graphic LCD’s, while the T6A40 is a row driver. They are compatible with Z80 based CPU’s and drives displays with up to 80 columns, resp. 68 rows. The display size of the TI-85 is 128 * 64 pixel, therefore a total of three drivers are necessary.
A serial port of the calculators allows the connection to the Calculator-Based Laboratory system CBL and the Calculator-Based Ranger CBR.
The TI-85 was within 2 years replaced with the TI-86.
You can check the ROM version of your TI-85 using the following key sequence and reading the number on your screen:
[2nd] [MODE] [ALPHA] [S]
Information provided by ticalc.org
and Xavier Andréani.
The TI-85 is permitted (as of September 27, 2007) for use on SAT, ACT, PSAT and AP exams.
If you have additions to the above article please email: firstname.lastname@example.org.
© Joerg Woerner, December 5, 2001. No reprints without written permission.