Texas Instruments TI-86

Date of introduction:  January 6, 1997
 Available: May 1997
Display technology:  LCD dot matrix
New price:  $150.00  Display size:  8 * 21 characters
Size:  7.2" x 3.2" x 0.80"
 182 x 81 x 20 mm3
Weight:  5.9 ounces, 165 grams Serial No:  07235848
Batteries:  4*AAA + CR1620 (35mA) Date of manufacture:  mth 11 year 1997 (E)
AC-Adapter:   Origin of manufacture:  Taiwan (I)
Precision:  14 Integrated circuits:  CPU: Toshiba T6A43
 ROM: AT27C020
 RAM: SRM20100
 Display: T6A40,
Program steps:  96k Bytes Courtesy of:  Mark Bollman

TI-86_1_Back.jpg (140990 Byte)The TI-86 added more functions and memory to the it's predecessor TI-85 and carried the new, smoother housing.

The main features of the TI-86 in a short summary:

Graphing of up to 99 functions at one time.
Parametric graphing to analyze up to three parametric equations.
Manipulation of matrices with dimensions of 80*80.
One- and two-variable statistical analyses with up to 6,000 data points.
Programs with a total of 96,000 Bytes.

Disassembling this TI-86 manufactured in November 1997 reveals no big surprises. It makes use of just 5 main components on the printed circuit boards (PCB’s):

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 approaches 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-86 the integration of the CPU into the ASIC. Learn more about the Hardware Architecture of TI’s Graphing Calculators.

ROM (Read Only Memory): The ROM contains the operating system of the calculator. The first products on the market used mask-programmable ROMs, the program was stored already during the production of the Integrated Circuit. Later calculators changed to Flash ROMs, 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.

This TI-86 manufactured already in 1997 makes use of an one-time programmable (OTP) ROM ATMEL AT27C020. Later TI-86 calculators host a Mask ROM LH532©98 manufactured by Sharp, Japan. It is common practice in software engineering to avoid the high one-time costs and long lead time of a Mask ROM during the ramp up of a new product. OTP ROM like the AT27C020 are on the other hand more expensive. Don't miss an even earlier TI-86 Engineering Sample with Flash ROM technology manufactured in February 1997, about 3 month before the calculator hit the shelves.

RAM (Random Access Memory): The Static RAM is used as data memory and is used to store both variables, user programs and intermediate results. This TI-86 makes use of SRM20100 chip manufactured by Epson, Japan. The capacity of the memory is 128k Bytes.

DISPLAY: The Toshiba T6A23 is a column driver for small-to-medium-sized dot matrix graphic LCD, while the T6A40 is a row driver. They are compatible with Z80 based CPUs and drive displays with up to 128 columns, resp. 64 rows. The display size of the TI-86 is 128 * 64 pixel, therefore one display driver each is necessary.

A special "teacher version" called TI-86 VSC combines the standard TI-86 features with a port to connect to a ViewScreen panel via a cable. Placing the panel on the overhead projector enlarges the image of the handheld screen so that each student can follow along.

A serial port of the calculators allows the connection to the Calculator-Based Laboratory system CBL, its successor CBL 2, the Calculator-Based Ranger CBR and its successor CBR 2.

Don't miss the colorful slide cases developed for the TI-83 Plus, they fit on the TI-86, too.

Don't miss the TI-89, a pocket sized Symbolic calculator.



You can check the ROM version of your TI-86 using the following key sequence and reading the number on your screen:

[2nd] [MODE] [ALPHA] [S]

Information provided by and Xavier Andréani.

Exam acceptance:

The TI-86 is permitted (as of September 27, 2007) for use on SAT, ACT, PSAT and AP exams.

Obsolete / Discontinued Products:

The TI-86 Graphing Calculator has been discontinued (as of June 8, 2008) and is no longer available at most retail locations. 

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© Joerg Woerner, August 3, 2008. No reprints without written permission.