Texas Instruments TI-36X Pro (Version 2)

Date of introduction:  March 2021 Display technology:  LCD dot matrix
New price:  $28.00 (SRP 2021) Display size:  4 * 16 characters
 (5 * 19 for menus)
Size:  6.8" x 3.2" x 0.6"
 172 x 83 x 15 mm³
Weight:  4.2 ounces, 120 grams Serial No:  
Batteries:  Solar cells + CR2032 Date of manufacture:  mth 03 year 2021 (E)
AC-Adapter:   Origin of manufacture:  Philippines (L)
Precision:  13 Integrated circuits:  
Memories:  8    
Program steps:   Courtesy of:  Joerg Woerner

Texas Instruments shifted in 2015 production of the TI-36X Pro from China to the Philippines before in quietly changing in March 2021 its design. The formerly silverish navigation button on the upper right of the keyboard changed the color to a standard grey. Everything else seems to be identical with its predecessor.

Instead of the then novel 2-line display of the TI-36X II, its successor TI-36X Pro features a dot matrix display with 31 * 96 addressable pixels allowing the calculator to display equations as they would be printed in a text book. 

In addition to this so called "MathPrint" mode the calculator sports a TI-36X II compatible "Classic" mode.

Compared with the original TI-36X II, in the US the quasi-standard for pupils, we notice a huge variety of functions:

• Classic (compatible with TI-36X II) and MathPrint Mode
• EOS with 8 pending operations and 23 levels of parentheses
• 8 memory variables x, y, z, t, a, b, c, d
• Data editor and list formulas: 3 lists, each up to 42 items
• Function table
• Toggle key fractions and decimals
• Equation entries up to 80 digits
• Complex numbers
• HEX, BIN and OCT logic and conversions
• Least common multiple, Greatest common divisor, Prime factors
• Numeric derivative
• Numeric integral
• Matrices, Vectors
• Numeric equation solver
• Polynomial solver
• Expression evaluation
• 20 physical constants and 20 conversions


Dismantling this TI-36X Pro with Date code L-0321E and manufactured in March 2021 in the Philippines reveals a pretty common construction with two printed circuit boards (PCBs). The main PCB hides the single-chip calculating circuit under a small protection blob of black epoxy and drives the graphing display with a heat sealed fine-pitch connector. The keyboard makes use of a much simpler second PCB and a heat sealed connector, too. The prominent SR-21 designation on the main PCB proves that this calculator was manufactured by Kinpo Electronics, Inc., a famous company located in Taiwan and doing calculator production for well established companies like Texas Instruments, Hewlett Packard, Casio, Canon and Citizen.

Inspecting the PCB of this TI-36X Pro calculator brought our attention to two small marks reading SR21P and SR21/SR21B-21-1, we noticed similar marks already with other Slide Rule calculators manufactured by Kinpo Electronics and started compiling a list of the PCB-Marks on calculators manufactured by OEMs for Texas Instruments.


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© Joerg Woerner, August 3, 2023. No reprints without written permission.