Texas Instruments TI-35

Date of introduction:  1979 Display technology:  LCD
New price:  $33.00
 $21.95 (SRP Sep. 1980)
Display size:  8 (5 + 2)
Size:  5.3" x 2.9" x 0.35"
 134 x 74 x 9 mm3
Weight:  2.9 ounces, 82 grams Serial No:  3522386
Batteries:  2*LR43 Date of manufacture:  wk 48 year 1980
AC-Adapter:   Origin of manufacture:  USA (ATA)
Precision:  11 Integrated circuits:  TP0324-4NL
Memories:  1    
Program steps:   Courtesy of:  Joerg Woerner

The TI-35 was the next calculator following the TI-50 in the slimline epoch. Differences in functionality were small, in appearance great. Compared to the design of the TI-50 or TI-53 with their metal housing and molded keys this one looks really cheap. TI corrected this "failure" later with a stylistic enhanced TI-35. Compare it for your own.

Simply by comparing the designation of the integrated circuits of the calculators you'll get the first members of the slimline family:

• TP0320    (CD3201) TI Investment Analyst 
• TP0320    (CD3202) TI-30-II 
• TP0321    TI-50
• TP0322    TI-Business Analyst-II
• TP0323    TI-53
• TP0324    TI-35
• TP0326    TI-38 and TI-20

Don't miss the rare Business Card, probably the missing calculator using one of the TP032x chips.

If you dig deeper into the early slimline calculators you'll notice two different designs of the keys itself. The cheap looking black keys like the ones on the left (1979) or the engraved keys started in the year 1978 with the TI-50. Some calculators used both keyboard:

Old style keyboard New style keyboard
Calculator Introduced Calculator Introduced
TI-30 II 1982 TI-30 II 1982
TI-35 1979 TI-35 1982

A similar calculator was introduced with the TI-38. In Brazil a similar calculator was advertised as TI-35B.

TI-35B_PCB.jpg (66281 Byte)In 1978 Texas Instruments introduced the first CMOS calculator chips based on the TMS1000 Microcomputer family. The TP0320 architecture is similar to the TMC0980 chips introduced two years earlier for the TI-30 calculator. Main disadvantage of this family was the limited capacity with just 2k*9 bits ROM and 576 bits RAM (TMC0980, 9*16*4 bits) or 768 bits RAM (TP0320, 12*16*4 bits) resulting in simplified and sometimes inaccurate calculating algorithm.

The next generation of enhanced C-MOS calculator chips was introduced in 1981 with the TP0455 resp. TP0456 family. The third edition of the TI-35 received during its production time an upgrade to the CD4557 chip and the accuracy of e.g. the Calculator forensics test increased slightly:

Forensics Test (expected: 9.0000000)
Calculator Chip Result
TI-35 (1979) TP0324-4N 9.177087103
TI-35 (1980) TP0324-4NL 9.177087088
TI-35 (1982) CD4557 9.114640577

Recently an early TI-35 with a Calculator forensics test result of 9.177087103 was reported. We noticed two minor differences: The calculator chips reads TP0324-4N instead the common TP0324-4NL designation and the finish of the keyboard plate looks different. 

In 1984 the era of the slimline calculators was over and Texas Instruments introduced a family of four calculators manufactured in Taiwan:

• TI-30 III
• TI-35 II
• BA-35

If you are interested in the calculating accuracy of scientific calculators don't miss the Calculator forensics.

The US based company Jeppesen Sanderson developed a very interesting navigation computer called avstar based on this TI-35. Don't miss the MicroManager using a very similar approach for a completely different application.

Find here an excerpt from the Texas Instruments Incorporated leaflet CL-199J dated 1981:

TI-35 Student Math Kit

Problem-solving kit with Slimline TI-35 scientific calculator.

The powerful 54-function calculator is truly pocket portable and performs the most-needed slice rule functions as well as PI, factorial and constant for rapid calculations of even complex problems. Its bright, liquid display crystal display with scientific notation lets you work with even the smallest or largest numbers with ease. Built-in statistical capabilities include data entry, mean and standard deviation for both sample and population data. Versatile 4-key Constant Memory* feature lets you store, recall, sum data to memory and exchange memory with display. And it retains your data even when the calculator is off.
Student Calculator Math Book, an expanded edition of TI’s popular "Great International Math on Keys Book", offers even more information about calculator mathematics and is filled with how-to problems, puzzles and games.
Also included with the TI-35 and book are detailed owner’s manual and a vinyl carrying case.

* Registered Trademark of Texas Instruments Incorporated

© Texas Instruments, 1981


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© Joerg Woerner, December 5, 2001. No reprints without written permission.