Hand-held Calculators

Home > Hand-held Calculators

Texas Instruments
TI-2500 "Datamath" & similar models

The TI 2500 "Datamath" was Texas Instruments first calculator, launched in early summer 1972. It was very successful and several versions were produced over the next few years.  At a quick glance these models look similar, but the differences between the major versions are shown below.

Versions illustrated:

TI-2500 "Datamath", 1st. version

Texas Instruments 2500 “Datamath”, 1st version

TI-2500 "Datamath", 1st. version.

The first version of the Datamath can be distinguished by the combined CE/D key, which is used to Clear the last Entry and to refresh the Display, which extinguishes, except for the first digit, after the calculator has not been used for about 15 seconds.

This version is also the only one which has 6 AA rechargeable cells, see photograph below.

Texas Instruments TI-2500 "Datamath", 1st. version.

Distinctive features: The first in a long line of hand-held calculator models sold by the major integrated circuit manufacturer Texas Instruments.

Technical details:
Display is 8 digits, red LED.

4-functions.

Main integrated circuit - TI TMS0119 (here date coded 7238, i.e. week 38 of 1972).

7.2v (6x AA re-chargeable cells).

74 x 138 x 42 mm (3" x 5.5" x 1.7").

The Datamath was introduced in July 1972 and cost $149.99, but this was soon slashed to $119.95 in September 1972.

Made in U.S.A. & UK. This example was made in the UK.

This was the first calculator manufactured by Texas Instruments.
However, Texas Instruments had started research into portable calculators as early as in 1966 with the "Caltech" project. The company was a supplier of calculator electronics to Canon, who's Pocketronic calculator of 1970/71 was a much advanced Caltech design and was one of the first hand-held calculators.
By 1972, Texas Instruments had realised the huge potential of the pocket calculator and entered the market with the Datamath.  TI is one of the few early manufacturers which is still in the calculator market.

The development of the TI-2500 Datamath produced several similar versions, some of which are shown further down this page.

In hand

The TI-2500 "Datamath" is chunky but is definitely a hand-held calculator.

Rear

The rear of the 1st. version TI-2500 "Datamath" with the battery compartment cover removed revealing the six AA rechargeable Ni-Cad cells used in this model.  These were then very expensive.

Inside

The 1st. version TI-2500 "Datamath" with the case opened.  This shows that the bottom half, on the left, is the battery compartment which takes up the bulk of the volume inside.  On the right is the top half of the calculator showing the rear of the keyboard, against which the battery compartment fits.  The electronics, including the Texas Instruments TMS0119NC calculator chip, is tucked in around the display, at top right.

Display

Here the display board has been rotated upwards to show the LED arrays of the display, together with two SNSN75492 LED driver chips.

TI-2500 "Datamath", 2nd. version

TI 2500 “Datamath”, 2nd. version.

TI-2500 "Datamath", 2nd. version.

The second version has a key marked 'CE' only. It uses only 4 AA rechargeable cells.

Texas Instruments TI-2500 "Datamath", 2nd. version.

Display is 8 digits, red LED.

4-functions.

Main integrated circuit - TI TMS0119 (here date coded 7343, i.e. week 43 of 1973).

4.8v (4x AA re-chargeable cells).

74 x 138 x 42 mm (3" x 5.5" x 1.7").

This example was made in Great Britain.

Rear of the 2nd. version TI 2500

The rear of the 2nd. version TI-2500 "Datamath" showing that there is no battery cover for removal by the user.

with the case opened

The 2nd. version TI-2500 "Datamath" with the case opened.
The electronics of this version is similar, but not identical, to the 1st version and is mounted on a full sized circuit board behind the keyboard.
The 4 AA rechargeable Ni-Cad cells are attached to the base.

"Minimath" LCD prototype

TI 2500 Minimath LCD
TI 2500 Minimath LCD

There was an LCD version of the Datamath which was produced in prototype form as the Minimath, as shown on the left, but it was never marketed.
For more information see the "TI Prototype Found" article.

TI-2500 "Datamath", 3rd. version and
TI-2500B "Datamath"

TI 2500B “Datamath”

The  TI-2500 "Datamath", 3rd. version and TI-2500B "Datamath" are very similar and both can take replaceable batteries in the battery compartment.

Texas Instruments TI-2500 "Datamath", 3rd. version
and TI-2500B "Datamath".

From the outside, the TI-2500 3rd. version and the TI-2500B appear to be identical apart from the model number printed on the label on the back.  Unfortunately, all the printing has been rubbed off the label on the machine illustrated, so it is not possible to positively determine which of these two models it actually is.  The 'Datamath' website suggests that the 'B' designation indicates that the calculator is fitted with a Bowmar 'Opto-stick' display, rather than a display from Texas Instruments.  As noted in the article 'The Story of the Race to Develop the Pocket Electronic Calculator' calculator manufacturers had expected that Liquid Crystal Displays (LCDs) would take over from LEDs.  When this did not happen they fell back on LEDs which caused a shortage of these displays, which is probably why Texas Instruments used an LED from its competitor, Bowmar.  Since the calculator here does not have a Bowmar 'Opto-stick' display then it is likely to be a 3rd version TI-2500.

Display is 8 digits, red LED.

4-functions.

Main integrated circuit - TI TMS0119 (here date coded 7449, i.e. week 49 of 1974).

Uses either 3x AA re-chargeable cells or 4x AA disposable cells.

74 x 138 x 42 mm (3" x 5.5" x 1.7").

TI 2500B “Datamath” battery compartment

The rear of the 3rd. version TI-2500 or TI-2500B with the battery compartment cover removed.

Unusually, it takes four AA disposable cells, or only three rechargeable cells.

TI 2500B “Datamath” circuit board

The circuit board of the 3rd. version TI-2500 or TI-2500B with the TI TMS0119 calculator integrated circuit on the right.

TI-2500-II "Datamath II"

TI-2500 II “Datamath II”

Texas Instruments TI-2500-II "Datamath II".

The TI-2500-II "Datamath II" uses new electronics in the old style casing, and the keyboard now has a "%" key.

Display is 8 digits, red LED.

4-functions, %.

Main integrated circuit - TI TMS0803NC (here date coded 7522, i.e. week 22 of 1975).

Uses 2x AA disposable cells.

74 x 138 x 42 mm (3" x 5.5" x 1.7").

This example was made in Italy.

TI-2500 II “Datamath II” circuit board

The circuit board of the TI-2500-II "Datamath II".

TI-2510

TI-2510
Rear

TI-2510.

Is similar to the TI-2500 3rd. version and the TI-2500B.

Display is 8 digits, red LED.

4-functions.

Uses 4x AA disposable cells.

74 x 138 x 42 mm (3" x 5.5" x 1.7").

TI-2511

TI-2511

The TI-2511 is similar to the TI-2500 3rd. version and the TI-2500B.

Texas Instruments TI-2511.

Is similar to the TI-2500 3rd. version and the TI-2500B.

Display is 8 digits, red LED.

4-functions.

Main integrated circuit - TI TMS0119 (here date coded 7343, i.e. week 43 of 1973).

Uses 4x AA disposable cells.

74 x 138 x 42 mm (3" x 5.5" x 1.7").

Circuit board

The circuit board of the TI-2511.

Hand-held Calculators

Vintage Calculators

© Text & photographs copyright Nigel Tout   2000-2019  except where noted otherwise.