Active-Matrix Display Features

C H A P T E R 2

Hardware Modiﬁcations

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

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		60 ms typical
response time
Gray scale		16 levels

6	Active-Matrix Display Features