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ec 4000Model: EC-4000
Battery: BP6 , BP7
Adapter: AC9131, AC9132
Year: 1979
Chip: TMC1501          
Info:The Radio Shack EC-4000 does not only look like an early TI-57 Programmable, it's 100% identical. Please notice that Texas Instruments used in Italy a simple sticker instead the molded TI-logo and TEXAS INSTRUMENTS nameplate found with the US-built TI-57 Programmable.