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TI 15 overheadModel: TI-15 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".