Texas Instruments TI-2500B / Datamath

Date of introduction:  January 1974 Display technology:  LED-stick w/o lens
New price:  $69.95 Display size:  8
Size:  5.5" x 3.0" x 1.7"
 139 x 76 x 42 mm3
Weight:  6.7 ounces, 191 grams Serial No:  2500B487035
Batteries:  3*AA NiCd or 4*AA Alkaline Date of manufacture:  
AC-Adapter:  AC9130 or AC9120 Origin of manufacture:  USA
Precision:   Integrated circuits:  TMS0119
Program steps:   Courtesy of:  Joerg Woerner 
    Download manual:   (US: 2.4 MByte)

TI-2500B-Batt.jpg (29553 Byte)The Datamath TI-2500B could be easily recognized at the nice battery compartment on the bottom. This calculator uses either 3 rechargeable NiCd batteries or 4 alkaline cells. 

TI-2500B-Switch.jpg (55603 Byte)Dismantling the TI-2500B reveals a small switch to disconnect the charging current from the alkaline batteries. At a first glance the use of either 3 NiCd batteries (3*1.2V=3.6V) or 4 alkaline batteries (4*1.5V=6.0V) looks stupid. Thinking about the high cost price of rechargeable batteries in 1974 gives the answer.

TI-2500B_PCB.jpg (58368 Byte)The only known difference to the Version 3 of the Datamath is the letter "B" in the name and serial number. This could be a hint to the LED-display manufactured by Bowmar and marked Opto-Stick. Don't miss the first prototypes of the TI-2500B.

In October 1973 with the TI-2510 a Datamath with absence of rechargeable batteries was introduced.

A more detailed comparison between the ten known Datamath Versions could be found here.

In Spain a TI-2500B was manufactured with only 3 batteries under the hood.

A similar calculator to this TI-2500B was sold under the label of Longines Symphonette. View here.

Datamath™ is a trademark of Texas Instruments.

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