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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)

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.

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