Texas Instruments

Model: TI-2500 Longines Symphonette 1 version
Battery: 6 x AA ni-cd internal
Adapter: AC9100
Year: 1972
Chip: TMS0119
Info: This calculator sold by Longines Symphonette could be easily recognized as a Texas Instruments Datamath calculator. It followed the Electronic Calculator ioduced few month earlier. The main differences between the original and the badged calculators are the olive-green color of the housing, the grey keys and the Longines Symphonette.

• Datamath

Model: TI-2510
Battery: 4 x AA ni-cd internal
Adapter: AC9120
Year: 1975
Chip: TMS0119
Info:

• Datamath

Model: TI-2511
Battery: 4 x AA alkaline
Adapter: AC9900/e
Year: 1974
Chip: TMS0119
Info: 1 version

• Basic

Model: TI-2550
Battery: 3*AA NiCd or 4*AA Alkaline 
Adapter: AC9130 or AC9120
Year: 1974
Chip: TMS0601
Info: Released one year after the legendary TI-2500, the first with a lens display (like bubbles)

• Basic

Model: TI-2550 II
Battery: 2 AA or BP2
Adapter: 
Year: 1976
Chip: TMS1071
Info: