Most collectors of early electronic calculators will sooner or later ask themselves: „How old is this piece of history in my hands“? The answer is quiet easy, in conjunction with the pictured albums here in the Datamath Calculator Museum you get a rough estimate of the timeframe each calculator was built. Some models had a very short lifetime, e.g. the rare SR-16 was manufactured between October 1974 and early 1975. Other calculators stayed longer, the famous TI-68 was introduced 1991 and was available in some countries till the year 2000. If you inspect the calculators manufactured by Texas Instruments carefully you will notice small numbers stamped with ink on the body shell, embossed in the plastic mold or printed on the license plate. These numbers look typically like 314, 2676 ATA or I1090. If you study this article carefully you’ll learn that the first calculator is a Datamath Version 2 manufactured April, 1973, the second calculator was produced in the Abilene, TX facility and the third is a modern, Taiwanese LCD calculator. Interested in getting more information?
• Search the numbers
Starting with the introduction of both the Datamath and the early Desktop calculators Texas Instruments used visible ink to stamp the manufacturing date on the back of the calculator housing using a 3-digit code. Unfortunately in most cases the ink got lost over the time on the polished surfaces of the early calculators. Later models like the TI-2550 or Exactra line used a structured surface and the ink is more durable. Some calculators like the SR-50 got the date code printed on hidden places like the internal plastic frame below the battery pack. If you can read only parts of the numbers you should open the calculator and search the manufacturing date on the integrated circuits to limit the possible date range. Calculators introduced in the year 1976 or later use another coding with 4-digits embossed into the mold of the rear case shell. This method was durable, in some cases the readability is limited due to bad adjusted temperature or pressure of the tooling. With the TI-1750, the first Texas Instruments calculator produced in Japan another coding scheme using 3-digits was introduced. These early LCD-calculators with their metal housing got small adhesive license plates carrying the model designation, serial number, date and origin of manufacturing. Later far East products use a novel 4-digit coding for the date of manufacturing.
• Decipher the code
You should be able to decipher 5 different coding schemes of the manufacturing date to cover all calculators and related products manufactured by Texas Instruments. In addition you get in most cases the information of the place of manufacturing.
3-digit date code
Early calculators introduced between the years 1972 and 1975 make use of a three digit code to define the week and year of manufacturing.
Example: 314 reads as 31th week of the year 1974
You notice immediately that this code was not Y2K compliant and there was a need for another coding scheme.
The origin of the calculator is usually Dallas, TX if not otherwise noted. Only the TI-2500 / TI-3500 was reported to be produced in Italy, UK and Spain and the SR-10 / SR-11 in Brazil and Spain.
3-digit "Early Far East" date code
Calculators produced in Far East and Souteast Asia during the late 70s and early 80s use a three digit code to define the month and last digit of the year of manufacturing
Example: 104 reads as October 1984
The manufacturer of the calculator is coded with one letter and the origin written in plain words. A table is given with the 4-digit "far East" code.
4-digit date code
Calculators introduced later than 1975 and not produced in Asia use a four digit code to define the week and year of manufacturing.
Example: 2676 reads as 26th week of the year 1976
The origin of the calculator is coded with three letters and / or written in plain words.
|El Salvadore||San Salvadore|
4-digit "Far East" date code
Calculators produced in Far East and Southeast Asia use a four digit code to define the month and year of manufacturing.
Example: 1090 reads as October 1990
The manufacturer of the calculator is coded with one letter and the origin written in plain words.
|L||Leo Electronics||Japan, China|
6-digit "European" date code
Calculators produced in Italy use sometimes a six digit code giving the day of production.
Example: RCI240595 reads as May 24, 1995
3-digit "European" date code
Both the Financial Investment Analyst and Fixed Income Securities calculators manufactured between 1988 and 1991 in Italy use a three digit code to define the week and year of manufacturing.
Example: 439 reads as 43th week 1989
The years 1990 and 1991 are encoded with the digit 0 resp. 1.
3¼-character "Radio Shack" date code
Calculators manufactured for Radio Shack in the Seventies, Eighties, and Nineties usually sport a 3-character or 4-character date code.
Example: 1A5 reads as 1st month 1985 or 1995. The character A is just serving as a separator between month and year.
4-digit "Integrated Circuit" date code
Most Integrated Circuits (ICs) manufactured by Texas Instruments or Toshiba use a four digit code to define the week and year of manufacturing.
Example: 7424 reads as 24th week of the year 1974
The origin of the IC is written in plain words. Early Texas Instruments ICs manufactured by Texas Instruments using a metal–oxide–semiconductor (MOS) process, use a TMS designation and we learned from the TMS1000 and TMS7000 documentation the TI Standard Symbolization: TMX, TMP, and TMS are representative of the evolutionary stages of product development from engineering prototypes through fully qualified production devices:
|• TMSxxxx Experimental devices that are not representative of the final device's electrical specifications and has not completed reliability verification
• TMPxxxx Final silicon die that conforms to the device's electrical specifications but has not completed quality and reliability verification
• TMSxxxx Fully qualified production devices
Devices with on-chip ROM (Read-only Memory) usually include a Cxxxx or CDxxxx reference and might have two different © information:
|• ©19xxTI Texas Instruments Microcode copyright
• ©19xxTI Texas copyright of ROM Code
3-character "Japan Integrated Circuit" date code
Most integrated circuits (IC‘s) manufactured by Hitachi and some other Japanese companies use a three digit/letter/digit code to define the year, month and week of manufacturing.
Example: 3B4 reads as 4th week within February of the year 1973
The origin of the IC is written in plain words.
4-character "Sharp Integrated Circuit" date code
Most integrated circuits (IC‘s) manufactured by Sharp in the 1980s use a four character code to define the year, month and week of manufacturing.
|• First Character: Identification Number
• Second Character: Last digit of production year
• Third Character: Production month
• Forth Character: Production week
Example: 538A reads as 1st week within August of the year 1983
|A||1st Week of Month|
|B||2nd Week of Month|
|C||3rd Week of Month|
|D||4th Week of Month|
|E||5th Week of Month|