Texas Instruments TI-1788 III

Date of introduction:  1984 Display technology:  LCD
New price:   Display size:  8
Size:  3.9" x 2.3" x 0.3"    
Weight:  1.6 ounces Serial No:  10108034
Batteries:  2*LR43  Date of manufacture:  mth 09 year 1985
AC-Adapter:   Origin of manufacture:  Taiwan (C)
Precision:  8 Integrated circuits:  Toshiba T6798S
Memories:  1    
Program steps:   Courtesy of:  Joerg Woerner
    Download manual:   (DE, GB: 1.4 MByte)

TI-1788III_1.jpg (10871 Byte)The TI-1788 III combines the clock and alarm time function known from the TI-1788 II with a whole set of additional functions and includes:

8-digit calculator including full memory
Clock with alarm time and buzzer
World Time
Calendar with Day of Week function
Stopwatch with intermediate results
Conversion capability (multiplies with and divides by a constant)

Compared with the TI-1790 introduced about 6 years earlier size and weight was reduced dramatically. 

Dismantling the featured TI-1788 III manufactured in September 1985 by a non-disclosed Original Equipment Manufacturer (OEM) reveals a clean design centered around a Toshiba T6798S single-chip calculator circuit soldered on a double-sided printed circuit board (PCB) and powered by two small LR43 batteries. The only additional components are the 8-digit LC-Display and a small buzzer for the alarm. We know the Toshiba T6798S chip already from the Canon LC-64T dropping the [WT] key (World Time) to use a more traditional 5x5 keys layout allowing a smaller package of the calculator.

Inspecting the PCB of this TI-1788 III calculator brought our attention to a small mark reading CC-31T-11, similar marks could be found with the TI-1788 and TI-1788 II. We are almost positive that the TI-1788 III was manufactured by Cal-Comp Electronics. We started compiling a list of the PCB-Marks on calculators manufactured by OEMs for Texas Instruments.

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Joerg Woerner, October 10, 2003. No reprints without written permission.