Texas Instruments

• LCD-1980-1984

Model: TI-1100
Battery:  LR43       
Adapter: 
Year: 1990
Chip: Toshiba    
Info:    

• LCD-1982-1987

Model: TI-12 math explorer
Battery: solar
Adapter: 
Year: 1988
Chip:  T6m39s Toshiba
Info:  modern LCD  1982 - 1987

• LCD-1991-1999

Model: TI-12 math explorer
Battery: solar
Adapter: 
Year: 1998
Chip:  T6m39s Toshiba
Info:  China. The Math Explorer ( TI-12) is another calculator introduced by Texas Instruments to perform fractional arithmetic for elementary school. 

• Overhead

Model: TI-12 intermediate overhead
Battery: 
Adapter: 
Year:  
Chip: made in China
Info:  The California based company Stokes Publishing Company, Inc. distributes under the label "The Educator®"
calculators optimized for teaching purposes. William T. Stokes filed already July 30, 1991 the US Patent Application U.S. Pat. No. 5,035,502
 with the title "Transparent calculator for overhead projection".

• Basic

Model: TI-1200
Battery: 9 volt
Adapter: 
Year: 1975
Chip: TMS0952
Info: Introduced in March 1975, the TI-1200 started together with the TI-1250 a great career with millions and millions units manufactured over the course of about 2 years. As a successor to both the stylish TI-1500 and the Exactra line, the TI-1200 demonstrated already the impressive design and technical engineering behind the TI-30.