Terminated: 1973
A lot of info about the TI-2500 can be found on the excellent site http://www.datamath.org (link validated 2024-01-13)
The TI-2500 is a plain four-function calculator. A switch lets the user choose between chained and constant calculatons.
The following text is from the back of the calculator itself:
Built-in battery gives 4-6 hours of portable operation — full recharge in 16 hours. Power saver circuit turns off display — except for 1st digit — 15 seconds after last operation. Restore display by pressing CE/D key. Low battery is indicated by lighted decimals. Calculator can be operated during recharge.
The serial number table (serial number 2500-80005) at the back of
my TI-2500 shows "Rev. D".
According to this Datamath page (link validated 2024-01-13), the TI-2500 in my collection is from the second series, made between October and December 1972, in Dallas, Texas. But I am a bit puzzled because mine has four instead of six NiCad cells.
To be on the safe side the (Varta) NiCad cells (shown on the right) were taken out of this calculator. Whilst this calculator is therefore not in its original state anymore I prefer to take rechargeable batteries out because of the danger of leaking cells.
Many thanks to Mr. Huseyin Avni Cinemre from Turkey who was so kind to donate this calculator to the museum.