Texas Instruments TI-73 Explorer

Date of introduction:  July 2006 Display technology:  LCD dot matrix
New price:  $69.99 (SRP 2006) 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:  2481005552
Batteries:  4*AAA + CR1620 (35mA) Date of manufacture:  mth 03 year 2008 (G)
AC-Adapter:   Origin of manufacture:  China (P)
Precision:  14 Integrated circuits:  ASIC: TI REF TI-738X
 Flash: 29LV400
 Display: Novatek NT7564H
Program steps:  25k Bytes, 128k Bytes Flash ROM Courtesy of:  Joerg Woerner

TI-73_P0803G_P1.jpg (389711 Byte)Texas Instruments introduced the original TI-73 already in 1998 as the first graphing calculator dedicated for the middle grades. It was never a great success but served as a foundation for the TI-83 Plus, the best selling graphing calculator in the US and Canada. Texas Instruments reported more than 2,000,000 shipped units in 2000!

In the fast moving world of electronics and manufacturing technology it was for sure that we will see a lot of improvements of the technical twins TI-73 (Explorer) / TI-83 Plus till their discontinuation. In March 2009 the TI-73 Explorer received a major upgrade in the appearance to match the TI-84 Plus series and we acquired this late "old" TI-73 Explorer manufactured in March 2008. 

TI-73_P0803G_PCB.jpg (317729 Byte)TI-73_P0803G_Back.jpg (234062 Byte)Comparing this calculator with the original TI-73 Explorer design reveals a lot of internal differences.

The original design of the TI-73 Explorer made use of 5 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

The new designed printed circuit board (PCB) needs just 3 Integrated Circuits:

ASIC: Z80 microprocessor, RAM and supporting logic
Spansion 29LV400 512k Bytes Flash ROM
Novatek NT7564H: Single-chip 64*120 pixel display driver

TI-73_P0803G_ASIC.jpg (76176 Byte)The picture on the right gives an enhanced view of the ASIC "TI REF TI-738X" that clocks the Z80 microprocessor with 6 MHz and incorporates the 32k Byte RAM and some supporting logic. Learn more about the Hardware Architecture of TI’s Graphing Calculators. The ASIC was probably manufactured by Toshiba and recalls us the TI-83 Plus Silver Edition with the "TI-REF 83PL2M/TA2" ASIC and the early TI-84 Plus with its "TI-REF 83PLUSB/TA2" ASIC. This ASIC "TI-REF TI-738X" was obviously used in the revised TI-83 Plus, too.

TI-73_P0803G_LC.jpg (63426 Byte)The driver circuit of the LC-Display was traditionally manufactured by Toshiba for Texas Instruments' graphing calculators. This TI-73 Explorer manufactured in March 2008 shows with the Novatek NT7564H a one-by-one replacement. It is just a bare chip mounted on a flexible piece of circuit board attached between the display and the main PCB.

We prepared together with fellow collector Xavier Andréani a comprehensive comparison of entry level graphing calculators, to shed some light on the different specifications of the TI-82 and TI-83 / TI-83 Plus based products.

In 2009 the TI-73 Explorer morphed into the skin of the TI-84 Plus but lacked any additional features, for instance the USB interface and higher clock frequency. 

A special "teacher version" called TI-73 Explorer 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.

Don't muss the colorful slide cases developed for the TI-83 Plus, they fit on the TI-73 Explorer, too.

Stokes Publishing Company, Inc. based in Sunnyvale, California sold a companion for the teacher, view the wonderful TI-73 Explorer.

Explorer™ is a trademark of Texas Instruments.


TI-73_P0803G_OS.jpg (60011 Byte)1.90 (February 6, 2006)
1.91 (March 20, 2008, actual in February 2009) 

You can check the ROM version of your TI-73 Explorer 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 Explorer is permitted (as of September 27, 2007) for use on SAT, ACT, PSAT and AP exams but is not recommended for the AP exam.

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If you have additions to the above article please email:

© Joerg Woerner, February 17, 2009. No reprints without written permission.