DATAMATH CALCULATOR MUSEUM
Texas Instruments TI-85 ViewScreen™
|Date of introduction:||1990||Display technology:||LCD dot matrix|
|New price:||Display size:||8 * 21 characters|
|Size:|| 6.5" x 4.8" x
166 x 121 x 22 mm3
|Weight:||6.0 ounces, 170 grams||Serial No:||032198|
|Batteries:||Date of manufacture:||mth 02 year 1992|
|AC-Adapter:||Origin of manufacture:||USA (LTA)|
|Precision:||Integrated circuits:||2*Toshiba T7778A, T7900|
|Program steps:||Courtesy of:||Joerg Woerner|
TI-85 ViewScreen panel is connected with a flat-ribbon cable permanently to a
modified TI-85 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.
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-81 ViewScreen connected to the first generation TI-81 VSC. Main differences are the resolution of the LCD display and the added connector for an external AC adapter.
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© Joerg Woerner, February 23, 2009. No reprints without written permission.