Texas Instruments TI-83 PLUS ViewScreen™ (Prototype)

The TI-83 Plus ViewScreen Calculator (VSC) is the teacher version of the standard TI-83 Plus. It connects with a special port to a ViewScreen panel via a cable. Placing the panel on the overhead projector enlarges the image of the handheld screen so that each student can follow along. Don't miss the mystery Texas Instruments XX-X Graphing calculator, actually a very early prototype of the TI-83 Plus VSC.

The display of the TI-83 Plus sports 64 * 96 dots compared with the 64 * 128 dots of the TI-86 or the 100 * 160 dots of the TI-89. As a consequence introduced Texas Instruments different ViewScreen panels.   

Four ViewScreen panels were available in 2008:

As an alternative the TI-Presenter video adapter connects to a TV or other projection device with a video input port. 

From a technical point of view the TI-83 Plus VSC is almost identical with the students TI-83 Plus. The first difference you notice is a slightly changed bottom shell of the calculator housing to accommodate the ViewScreen connector. Removing the cover for the small backup battery reveals a small wire - together with the missing serial number -  a strong hint towards a Prototype calculator used for design validation purposes.

Dismantling this TI-83 Plus VSC Prototype without Date code manufactured in December 1998 by Inventec Corporation in Taiwan reveals a total of three printed circuit boards (PCBs) with five main Integrated Circuits.

Main PCB:

Display PCB:

Driver PCB:

A third PCB is connected with a short piece of flat-cable to the display board. This PCB basically buffers the signals of the LC-Display and feeds them to the external ViewScreen connector.

CPU: The Zilog Z84C0008 microprocessor, a low-power CMOS-version of the original Z80 developed in 1974 and introduced in 1976. It is probably the same design as the Toshiba TMPZ84C00 chip found in some graphing calculators. Learn more about the Hardware Architecture of TI’s Graphing Calculators.

ASIC (Application Specific Integrated Circuit): The Z80 is a pure microprocessor and lacks, compared to so-called microcontrollers, any peripherals and housekeeping circuits. Texas Instruments developed already for the TI-82 in 1993 a support ASIC for the Z80 microprocessor based on the Toshiba TC14L gate array family with 1,000 usable gates in 1.0um CMOS-technology. This chip-set replaced the Toshiba T6A43 Application Specific CPU found in the earlier TI-81 designs. We assume that the TI REF 9815455 ASIC used in this TI-83 Plus VSC Prototype is based on a later Toshiba gate array family. 

Within the graphing calculator line of Texas Instruments you'll find different approaches for the CPU architecture:

• Application Specific CPU, e.g. the T6C79 found in the TI-83
• Discrete CPU with support ASIC, e.g. the Z80 / TI REF 9815455 combination of this TI-83 Plus VSC Prototype
• Gate array with embedded processor core and RAM, e.g. the TI REF 738X
   found in this TI-83 Plus manufactured by Inventec Corporation.

ROM (Read Only Memory): The ROM contains the operating system of the calculator. The first products on the market used mask-programmable ROM, the program was stored already during the production of the Integrated Circuit. Later calculators changed to Flash ROM, a technology allowing the programming of the software during the final production stage of the calculator. With the TI-83 Plus and all later graphing calculators from Texas Instruments even the user was able to reprogram the operating system. The Flash ROM 29F400 of this TI-83 Plus VSC Prototype was manufactured by AMD and has a capacity of 512k Bytes.

RAM (Random Access Memory): The RAM is used as data memory and is used to store both variables, user programs and intermediate results. This TI-83 Plus VSC Prototype makes use of one SRM2B256 chip manufactured by Epson (formerly Suwa Seikosha), Japan. The capacity of the memory is 32k Bytes.

DISPLAY: The Toshiba T6A04 is a column and row driver for small-to-medium-sized dot matrix graphic LCD. It is compatible with Z80 based CPUs and drives displays with up to 120 columns and 64 rows. The display size of the TI-83 Plus is just 96 * 64 pixel, therefore only one display driver is necessary.

A serial port of the calculators allows the connection to the Calculator-Based Laboratory system CBL, its successor CBL 2, the Calculator-Based Ranger CBR and its successor CBR 2. Texas Instruments announced in June 2002 an optional full-sized QWERTY Keyboard for a more convenient entry of notes into the handhelds.

Don't miss the colorful slide cases developed for the TI-83 Plus, they fit on the mystery Texas Instruments TI-83 Plus VSC, too.

ROM-Versions:

1.03 (March 17, 1999) 
1.06
1.08
1.10
1.12
1.13 (April 2001)
1.14 (December 16, 2001)
1.15 (August 26, 2002)
1.16
1.17
1.18
1.19 (January 16, 2006, actual in February 2008)

You can check the ROM version of your TI-83 Plus VSC using the following key sequence and reading the number on your screen:

[2nd] [MEM] [1]

Information provided by ticalc.org and Xavier Andréani.

Exam acceptance:

The TI-83 Plus VSC is permitted (as of September 27, 2007) for use on SAT, ACT, PSAT and AP exams.

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

© Joerg Woerner, August 27, 2020. No reprints without written permission.