Texas Instruments TI-55 II (Taiwan)

Date of introduction:  August 1984 Display technology:  LCD
New price:   Display size:  8 + 2
Size:  5.8" x 2.8" x 0.85"
 147 x 72 x 22 mm3
Weight:  3.0 ounces, 84 grams Serial No:  1471966
Batteries:  2*LR44 Date of manufacture:  mth 12 year 1984
AC-Adapter:   Origin of manufacture:  Taiwan (I)
Precision:  11 Integrated circuits:  TP0456 (CD4555), TP0456 (CD4556)
Memories:  1-8    
Program steps:  56-0 Courtesy of:  Joerg Woerner

TI-55-II_1_Label.jpg (77204 Byte)This TI-55 II could be called a rare calculator. Actually it is a TI-55 III from the first production runs and uses still the TI-55 II designation. Currently we know TI-55 II with production codes between October 1984 and March 1985. Please note the missing hyphen in the TI-55 II, the original design was labeled TI-55-II.

If you search the differences to the later US or Italy built TI-55 III, focus on the description below the "=" key.

TI-55-II_1_PCB.jpg (272532 Byte)TI-55-II_1_BAT.jpg (53799 Byte)Dismantling this TI-55 II manufactured by Inventec Corporation in Taiwan late in 1984 reveals the CD4555 / CD4556 calculator chips soldered on a typical far-east designed printed circuit board (PCB). 

TI-55_PCB.jpg (129123 Byte)The picture on the right gives you an inside view of the three of the four different TI-55-II and TI-55-III discovered up to now. From left to right you find:

TI-55-II manufactured in 1981 in US. 
   Known for the bouncing keyboard introduced with the slimline calculators.
TI-55-II resp. TI-55-III manufactured by Inventec Corporation in Taiwan between
   1984 and 1985. The PCB used in Compal's calculators could be found here.
TI-55-III manufactured in 1986 either in US or Italy. 
   Uses far-east keyboard technology with conductive rubber together 
   with contact fingers on a flexible PCB.

This early TI-55 II was donated by Luís Pereira. Thanks!

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© Joerg Woerner, December 5, 2001. No reprints without written permission.