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Additional Pictures 

 

This early TI-81 with the Date code I-0990 was manufactured by Inventec in Taiwan
in September 1990. Please notice the missing space for the backup battery.  

The PCB (printed circuit board) of the TI-81 manufactured  
in September 1990 looks different from the later calculators.

The main components of the TI-81: Toshiba T6A49A Application Specific CPU,  unknown 1990 ROM and Toshiba TC5565A RAM. All Integrated Circuits of the calculator were manufactured not later than July 1990.

This early TI-81 graphing calculator makes use of three display drivers :
Two T7778A column drivers and one T7900 row driver.


If you have additions to the above article please email: joerg@datamath.org.

Joerg Woerner, January 27, 2009. No reprints without written permission.