DATAMATH CALCULATOR MUSEUM

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, CD4556
Memories:	1-8
Program steps:	56-0	Courtesy of:	Joerg Woerner

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.

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).

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!

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