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CHAPTER 2
Hardware Modifications
6
Active-Matrix Display Features
This chapter describes hardware features of the PowerBook Duo 250 computer that make
it different from the Macintosh PowerBook Duo computer. These features include
■
the active-matrix display
■
the inverter/speaker board
■
the 200 MB hard disk drive
Active-Matrix Display Features 2
The PowerBook Duo 250 display is an active-matrix liquid crystal display. It meets the
same form factors as the basic PowerBook Duo display, so no modifications are required
to the computer housing. Each pixel in the active-matrix display’s 640 x 400 pixel array is
controlled by a unique transistor, for a total of 256,000 transistors. The standard display
mode is black characters on a white background, simulating the look of a printed page.
With its high contrast ratio of 30: and response time of approximately 60 milliseconds, the
PowerBook Duo 250 display provides performance similar to that of a CRT video display,
with no cursor smearing or cursor submarining. Table 2-1 lists the features of the
active-matrix display.
Table 2-1
Active-matrix display features
Feature Description
Display matrix 640 x 400 pixels
Active pixel area 192 mm x 120 mm
Display area 199 mm x 127 mm, including black stripe outline
Standard display mode Black image/characters on white background
Contrast ratio 30:1 minimum
Pixel pitch 0.3 mm square, with black strip between pixels
to increase contrast
Pixel on/off switching speed or
response time
60 ms typical
Gray scale 16 levels