DATAMATH  CALCULATOR  MUSEUM

Texas Instruments TI-88 (PVT 2)

Date of introduction:  Never
 (Announced: May 26, 1982
 Cancelled: September 10, 1982)
Display technology:  LCD dot matrix
New price:  MSRP: $350.00 Display size:  10 (8 + 2)
Size:  6.2" x 3.3" x 1.6"
 157 x 85 x 41 mm3
   
Weight:  8.3 ounces, 236 grams Serial No:  0001101
Batteries:  BP88 (1*AA-NiCd) Date of manufacture:  wk 32 year 1982
AC-Adapter:  AC9133 Origin of manufacture:  USA (ATA)
Precision:  13 Integrated circuits:  TP0485 (CD2901), TP0485 (CD2902), 2*TP0530,
 2*TP0531, TP0532 (CD5402),
 SN77203
Memories:  120-0    
Program steps:  0-960 Courtesy of:  Viktor T. Toth
Download product announcement:   (US: 2.1M Bytes) Download manual - PREVIEW ONLY:   (US: 4.2M Bytes)

We wrote May 1982 when Texas Instruments printed the sales brochures of the TI-88 on glossy paper. The brochures promised the introduction of the TI-58C/TI-59 successor for Forth Quarter 1982 in a package matching the TI-55-II line - before we got word of the TI-66. Today we know more: The development of the TI-88 was finalized, the manuals printed, the first pre-production calculators worked perfectly and Texas Instruments canceled the whole project! Maybe one of the reasons was the introduction of the powerful Hewlett-Packard HP-41C calculator or the innovative Sharp PC-1211 Pocket Computer. Or the underestimated complexity of the TI-88 design. Or electrostatic discharge (ESD) issues of the Module contacts. Or the internal competition with the CC 40 Compact Computer. Or the keyboard problems encountered with the TI-55-II family of calculators. Or the decision of a Manager of TI's Consumer Electronic group to quit the calculator business...

Learn more about the demanding "Project X" initiated already in Summer 1977 and leading not only to the (failed) TI Programmable 88, but the TI-66 PROGRAMMABLE, failed TI-76 PROGRAMMABLE, Compact Computer CC 40, (failed Compact Computer CC 70) and last but not least the successful TI-74 BASICALC and TI-95 PROCALC.

As of today we researched almost twenty different TI-88 calculators with twelve different Builds or modifications (learn more about the Five Engineering Stages):

Owner Serial Number Build: Date of Manufacture
Joerg Woerner 9-26-81-35 Design Validation Test 1 ATA wk 39 year 1981
Joerg Woerner 9-26-81-43 Design Validation Test 2 ATA wk 39 year 1981
Heinz Nixdorf Forum t.b.d. Design Validation Test 2 t.b.d.
Joerg Woerner --- Clear-Case DVT 3 ATA wk 04 year 1982
Joerg Woerner 0000049 Design Validation Test 3 ATA wk (01)51 year 1981
Joao Oliveira NTC-3-4-30-82 Engineering Validation Test 1 ATA wk 17 year 1982
Joerg Woerner --- Production Validation Test 1 ATA wk 21 year 1982
Joerg Woerner 0000337 Production Validation Test 1 ATA wk 21 year 1982
Joerg Woerner 0000452 Production Validation Test 1 ATA wk 21 year 1982
Marie Lisa Collas 0000341 Production Validation Test 1.5 ATA wk 21 year 1982
Joerg Woerner 02 693 Firmware Engineering Device ATA wk 21 year 1982
Viktor T. Toth 0001101 Production Validation Test 2 ATA wk 32 year 1982
Joerg Woerner 0001073 Production Validation Test 3 ATA wk 32 year 1982
Known --- Clear-Case PVT 4 ATA wk 33 year 1982
Joerg Woerner 0002023 Production Validation Test 4 ATA wk 33 year 1982
Luis Gómez 0002055 Production Validation Test 4 ATA wk 33 year 1982
Monty McGraw 0002069 Production Validation Test 4 ATA wk 33 year 1982
Smithsonian Institute 0002074 Production Validation Test 4 ATA wk 33 year 1982

Just looking at the keyboard of the TI-88, you can easily differentiate between the three Engineering Stages identified so far:

[ALPH] Key [R/S] Key Build: Notes
Design Validation Test Grey [ALPH] key
No dot next to [R/S] key
Engineering Validation Test Red [ALPH] key
No dot next to [R/S] key
Production Validation Test Red [ALPH] key
Red dot next to [R/S] key

Please be aware that the faceplates of most of the surviving TI-88s were updated to the Production Validation Test design and the most reliable indicator of the Three-and a-Half Main Engineering Stages can be found with the Revision Number located on the printed circuit board (PCB):

PCB 3500: Design Validation Test DVT 1, DVT 2, DVT 3
PCB 7999: Engineering Validation Test EVT 1
PCB 8000: Engineering Validation Test PVT 1, PVT 1.5
PCB 8449: Production Validation Test PVT 2, PVT 3, PVT 4

If you are interested in the subtle differences between the ten different builds discovered as of today, please follow this link.

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

The display is alphanumeric and prompts system messages in readable English.
The Constant Memory™ covers program and user memory.
The Solid State Software™ concept allows the expansion of two cartridges, either application programs (CROM) or user memory (CRAM).
Beside the traditional key-stroke programming, a formula mode is available.
A real time clock adds time and date.
A small speaker generates sounds. 
A printer port accepts the PC-800 printer.
A Cassette Interface CA-800 allows the permanent storage of both programs and data with a tape recorder.

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.

A Texas Instruments price list printed in July 1982 suggested these MSRPs:

Product MSRP (July 1982)

TI-88 Programmable Calculator

$350.00

PC-800 Printer

$185.00

CA-800 Cassette Interface

$60.00

Constant Memory Modules CRAM

$50.00

Solid State Software Modules CROM

$40.00


Inside the TI-88

In 2002 the Patent application US4,447,881 filed by Texas Instruments in 1980 was discovered by Juergen Dobrinski and in 2020 a binder labeled "Project X" including schematics of a "TI-85" from the estate of CB Wilson was located by Jon Guidry and made available on his website www.hexbus.com. Together with hours and hours of reverse engineering based on the inside views of the five different TI-88 builds discovered so far and looking into various CRAM and CROM Modules, we understand the TI-88 calculator architecture pretty well. The design is centered around a 4-bit microcontroller of the TP0485 family called Master Controller with an associated TP0485 4-bit controller responsible for Timekeeping, Key Scan and I/O functions supported by both ROM (Read Only Memory), RAM (Read/Write Memory) and Display Drivers. We know a similar approach with two controllers already with the TI-55 II.

Dismantling this TI-88 from the PVT 2 (Production Validation Test 2) series manufactured in August 1982 by Texas Instruments in their Abilene, TX facility, reveals a design using the following main components:

CD2901 (TP0485) Timekeeping, Key Scan and I/O Controller 
CD2902 (TP0485) Master Controller 
2*TP0530 Cascadable Display Drivers 
2*TP0531 On-board Read/Write Memories
CD5402 (TP0532) On-board Read Only Memory
Plug-in Memories which may be either Read Only Memory or Read/Write Memory
SN77203 Display Interface Voltage Controller Chip

The Schematics Diagram from the Patent application of "Product X", leading over "Product 225 TI-85" to the final TI-88 design, omits unfortunately the chip numbers but we could reverse engineer them accordingly.

Learn more about the components used with the TI-88 printed circuit board (PCB) including the Microcomputer Units (MCUs), Customer Read Only Memory (CROM), Customer Random Access Memory (CRAM), and Display.

POWER SUPPLY: We assume that all Integrated Circuits were manufactured in a low-power CMOS process, nevertheless used Texas Instruments once again a rechargeable battery pack labeled accordingly BP88. Instead of the 3 AA-sized NiCd cells of the TI-59 introduced in 1977, used this design of 1981 just one AA-sized cell and a step-up converter SN77203 to generate both the supply voltage of the Integrated Circuits and LC-Display. The battery is recharged with an AC9133 AC-Adapter, technically very similar to the AC9132 used with the TI-30 and other calculators but using a different connector.

ALGORITHM: 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 similar precision.


CRAM and CROM Modules

The TI-88 accommodates up to two modules in the rear slots.

Two different type of modules were designed:

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

With 0, 1 or 2 CRAM-Modules you get a total of:

CRAM-Modules Default Max. Program steps Max. User memory
  Program steps User memory Program steps User memory Program steps User memory
0 480 60 960 0 0 120
1 480 208 2144 0 0 268
2 480 356 3328 0 0 416

Dismantling a CRAM-Module from the final TI-88 PVT 4 Build reveals two TP0531 Read/Write Memories with 4,800 Bits or 600 Bytes capacity, each and a Sanyo 3 Volts lithium battery with 24.5 mm diameter and a thickness of 3.5 mm - matching today's CR2430 cells.

 CROM-Modules as pre-programmed software like the earlier TI-58C/TI-59 Solid State Software™ modules with up to 15,000 program steps.
   Eight modules were already defined in the sales brochures:

CROM-Module Content
1 Master Library
2 Statistics Library
3 Electrical Engineering Library
4 Finance Library
5 Surveying Library
6 Mathematics Library
7 PGM Development Library
8 Chemical Engineering Library

Dismantling a Master Library CROM-Module with a © 1982 marking from the final TI-88 PVT 4 Build reveals one TP0532 Read Only Memory with Custom Software CD5403 with 120,000 Bits capacity organized as 15,000 Bytes.

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:

Calculator Introduction
TI-18 1982 A BASIC calculator with a SCIENTIFIC appeal
TI-38 1979 The odd sibling of the TI-50 and TI-53
TI-68 1989 How NOT to do a keyboard layout
TI-78 1990 Too late? Too advanced? Who knows... 
TI-88 (1982) Killed by competition?
TI-98 (2002) Just a fantasy number, but it would fit.

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

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

horizontal rule

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

© Joerg Woerner, October 10, 2019. No reprints without written permission.