Texas Instruments TI-81 ViewScreen™

Date of introduction:  1990 Display technology:  LCD dot matrix
New price:   Display size:  8 * 16 characters
Size:  6.5" x 4.8" x 0.85"
 166 x 121 x 22 mm3
Weight:  6.0 ounces, 170 grams Serial No:  003944
Batteries:   Date of manufacture:  mth 11 year 1990
AC-Adapter:  n.a. Origin of manufacture:  USA (LTA)
Precision:    Integrated circuits:  2*Toshiba T7778A, T7900
Program steps:    Courtesy of:  Joerg Woerner

TI-81VSC_1.jpg (249465 Byte)The TI-81 ViewScreen panel is connected with a flat-ribbon cable permanently to a modified TI-81 graphing calculator. Placing the panel on a raised platform with an additional lens on the overhead projector enlarges the image of the handheld screen so that each student can follow along. The used platform was in the 90s commercially available from the Polaroid Corporation to project Polaroid color-graph type 691 overhead transparencies.

TI-81VS_PCB.jpg (410559 Byte)TI-81VS_Back.jpg (249170 Byte)Dismantling an early TI-81 ViewScreen manufactured end of 1990 reveals no surprises. The reflective background surface was removed from a standard TI-81 graphic LCD display to achieve a transmissive characteristic. The remaining circuit looks really straightforward and consists of two Toshiba T7778A column drivers and one T7900 row driver.

Don't miss the similar TI-85 ViewScreen connected to the first generation TI-85 VSC.

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© Joerg Woerner, February 12, 2009. No reprints without written permission.