Texas Instruments TI-88

We wrote the year 1982 when the calculator manufacturer Texas Instruments printed the sales brochures of the TI-88. The printed papers promised the introduction of the TI-58C/TI-59 successor in the year 1983. Today we know more: The development of the TI-88 was finished, the manuals printed, the first pre-production calculators worked perfectly and someone canceled the whole project! Maybe one of the reasons was the powerful Hewlett-Packard HP-41C calculator.

Currently we know six TI-88 that survived:

Viktor T. Toth acquired his rare pre-production model on eBay in the year 2000 for an undisclosed amount of money. The TI-88 pictured in the Datamath Calculator Museum was sold by the first owner in June 2006 for $175.00 or half of the original MSRP of $350.00. Some of the information about the TI-88 is either from the sales brochures or the manual.

Compared with the TI-58C you'll notice some differences and similarities:

It is a pity that the TI-88 with the perfect prompting system never made it to the market. The next calculators in the "Programmable/Scientific line" are the TI-95 PROCALC and the first Graphing calculator TI-81.

Interested in failed calculators? Don't miss the first SR-40 scheduled for release in 1975.

A Texas Instruments price list printed in July 1982 suggested these MSRP's:

Inside the TI-88

Recently the Patent application US4447881 filed by Texas Instruments in the year 1980 was discovered from Juergen Dobrinski. Together with an inside view of the two TI-88 we understand now the calculator architecture. The design is centered around a 4-bit microcontroller called Master Controller with two associated 4-bit controllers responsible for the arithmetics and the I/O. We got a similar approach with two controllers already with the TI-55 II. The overall design consists of:

The inside view gives you some chip numbers: CD2901, CD2902, CD5402 and TP0531. They are not yet discovered. The CD2901 and CD2902 are called TP0485, the CD5402 is called TP0532 in some documentation. The Schematics Diagram from the Patent application omits the chip numbers.

Running Mike Sebastian's "Calculator forensics"  gives a result of 9.000000955917. It took 7 years before  with the TI-68 another Texas Instruments calculator achieved a similiar precision.

We assume that all Integrated Circuits were manufactured in a low-power C-MOS process, nevertheless used Texas Instruments once again a rechargable battery pack. Instead of the 3 AA-sized NiCd cells of the TI-59 introduced on 1977 used this design of 1982 just one AA-sized cell. 


CRAM and CROM Modules

The TI-88 accommodates up to two modules in the rear slots. 
Two different type of modues were planned:

• CRAM-Modules as user programmable memory with either 1184 program steps or 148 user memories.

• CROM-Modules as pre-programmed software like the earlier TI-58C/TI-59 Solid State Software™ modules with 15000 program steps.
   Eight modules were already defined in the sales brochures:

Lucky Numbers?

People in China traditionally associate luck with numbers. As a rule in day-to-day life in China, it is customary to regard even numbers as being more auspicious than odd numbers. Eight, 'Ba' in Chinese has a similar sound to 'Fa', which means to make a fortune. All business men favor this number very much. However, for Texas Instruments the "8" in the type designation was not always a fortune.

We remember some very unlucky calculators:

History repeats - don't miss the story about the PET Project!

The TI-88 is featured in the Texas Instruments Announcement dated May 1982.

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

© Joerg Woerner, May 11, 2007. No reprints without written permission.