Texas Instruments TI-73

Date of introduction:  March 13, 1998
 Available: May 1998
Display technology:  LCD dot matrix
New price:  $95.00 Display size:  8 * 16 characters
Size:  7.2" x 3.2" x 0.80"
 182 x 81 x 20 mm3
Weight:  6.4 ounces, 182 grams Serial No:  09600104
Batteries:  4*AAA + CR1620 (35mA) Date of manufacture:  mth 01 year 1999
AC-Adapter:   Origin of manufacture:  Taiwan (I)
Precision:  14 Integrated circuits:  CPU: Zilog Z84C0008
 ASIC: TI REF 9815455
 Flash: AM29F400
 RAM: SRM2B256
 Display: Toshiba T6A04
Program steps:  25k Bytes, 128k Bytes Flash ROM Courtesy of:  Mark Bollman

TI-73_I0199_Back.jpg (125940 Byte)In 1998 Texas Instruments introduced with the TI-73 the first graphing calculator dedicated for the middle grades. It combines the features of the successful Math Explorer™ and Explorer Plus with the power and screen size of a graphing calculator.

TI-73_I0199_PCB.jpg (424991 Byte)Dismantling the TI-73 reveals a big surprise: The printed circuit boards (PCBs) of the TI-73 are identical with the later, more expensive TI-83 Plus. The only difference is the software inside the Flash ROM memory! Learn more about the Hardware Architecture of TI’s Graphing Calculators. This "original" TI-73 / TI-83 Plus design uses five main Integrated Circuits:

Zilog Z84C00 microprocessor
TI REF 9815455 ASIC
512k Bytes Flash ROM
32k Bytes Static RAM
Toshiba T6A04: Single-chip 64*120 pixel display driver

TI-73_I0199_ASIC.jpg (349579 Byte)The picture on the right gives an enhanced view of the ASIC "TI REF 9815455"  integrating some support logic. 

TI-73_I0199_LC.jpg (111619 Byte)A component not easily detected on the printed circuit board (PCB) of the TI-73 Explorer is the driver circuit of the LC-Display. It is just a bare chip mounted on a flexible piece of circuit board attached between the display and the main PCB.

In the history of TI's graphing calculators it is the successor of the TI-80 introduced in 1995.

The design of the TI-73 influenced even the TI-82 and TI-83, please focus on the rounder shape of the keys. In 2003 the color of the housing was changed to match with the TI-15 Explorer and the nameplate changed to TI-73 Explorer.

A special "teacher version" called TI-73 VSC combines the standard TI-73 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.

The TI-73 was mentioned in TI's press release dated August 15, 2002 to celebrate the 35th anniversary of its invention of the electronic calculator.

Math Explorer™ and Explorer Plus are trademarks of Texas Instruments.


TI-73_I0399_OS.jpg (51686 Byte)1.3004
1.3007 (August 7, 1998)
1.40 (June 22, 1999)
1.50 (May 2001)
1.60 (December 16
, 2001)

1.90 (February 6, 2006)
1.91 (March 20, 2008, actual in February 2009)

You can check the ROM version of your TI-73 using the following key sequence and reading the number on your screen:

[2nd] [MEM] [1]

Information provided by and Xavier Andréani.

Exam acceptance:

The TI-73 is permitted (as of September 27, 2007) for use on SAT, ACT, PSAT and AP exams but is not recommended for the AP exam.


Find here the original press release dated March 13, 1998:

Texas Instruments introduces upgradable graphing calculator for the middle grades market

DALLAS, March 13, 1998

Texas Instruments today introduced the TI-73 with Graph Explorer Software, a new upgradable graphing calculator designed specifically for math and science coursework in grades five through nine. The TI-73 features Flash technology which allows teachers to upgrade the calculator's functionality with the latest software versions, and customize the learning tool with specific applications to more closely meet their needs in the classroom.

"Teachers told us that they appreciated the increased functionality and benefits that new calculators offered, but they didn't want to purchase a new classroom set every three to five years, " said Tom Ferrio, vice president, Texas Instruments. "By incorporating Flash technology into our new TI-73 we've made it possible to upgrade the calculator electronically instead of purchasing a new unit, making it easier and less expensive to have the latest software version."

"Our funding sources do not allow us to continue purchasing calculator products every three years," said Pam Giles, K-12 mathematics and staff development consultant for Jordan School District , Sandy , Utah . "However, we can afford to purchase software upgrades, so the Flash technology will allow us to upgrade our TI-73 calculators to meet the changing needs of our teachers and students."

Flash upgrades and customization to the TI-73 will be made through the calculator's I/O port. The latest software version, as well as applications, can be downloaded from the TI website to the user's computer, then to the Flash-based calculator via TI-GRAPH LINK™.

TI is already creating additional applications such as a number and fraction line and geoboard, and is working with third-party software developers to create other applications or convert existing software programs to run on the TI-73.

Sunburst Communications, Inc., a long-time developer of award-winning educational software, has already teamed with TI to adapt some of its most popular software titles to the new calculator including Puzzle Tanks, Building Perspectives and Safari Search.

"The power to customize calculators will allow teachers to differentiate math and science curriculum," said Ms. Giles. "So that as calculators are moved from classroom to classroom they can be made software-specific to the subject at hand."

TI worked closely with teachers to deliver the specific functionality, look and feel they wanted in a graphing calculator.

"The color, keyboard layout and functionality are all geared for the middle grades classroom," said Ferrio. "Teachers said they didn't want features that weren't appropriate for middle grades because it could confuse and intimidate students, so we cleaned up the keyboard and reduced the number of second functions."

The TI-73 comes loaded with Graph Explorer Software, which contains the popular features from the Math Explorer™ and Explorer Plus™ along with increased power and additional features of a graphing calculator. The calculator's features have been refined to complement the middle grades curriculum with the capability for pictographs, pie/bar charts, stacked fractions, constants and data analysis.

"Teachers in middle grades are looking to graphing calculators as technology tools for many of the same reasons as teachers in high school and college," said Ferrio. "The teachers and students see the calculator as providing a viable alternative to computers, which cannot be relied upon for use by every student every day for classwork and homework."

"The Graph Explorer Software in the TI-73 provides the specific teaching tools that middle grades teachers asked for," Ferrio added. "We didn't try to include the most sophisticated mathematical functions, but we included features never seen in a graphing calculator that are designed for the topics taught in middle grades."

"I know of no other graphing calculators that have the horizontal and vertical bar charts, the pie charts, or the Manual-Fit line." said Ms. Giles. "These are concepts we use in the middle grades. With the TI-73, students can collect the data and analyze it themselves, using the math to help them make decisions."

Calculator-Based Laboratory™ (CBL™) and Calculator-Based Ranger™ (CBR™) applications are built into the TI-73 with Graph Explorer Software and allow users to conduct real-time, interactive data collection experiments with time, distance, temperature and other variables.

The TI-73 with Graph Explorer Software will be available in the U.S. and Canada during the second quarter of 1998 through instructional dealers at an estimated street price of $85-$95. New software and applications will vary in price depending on the particular application. Major software upgrades to the Graph Explorer Software will have an estimated street price equal to approximately half the price of a new calculator, and applications will have an estimated street price ranging from $5 to $20.


horizontal rule

If you have additions to the above article please email:

© Joerg Woerner, February 19, 2003. No reprints without written permission.