Apple 165c manual RAM Expansion Interface, LCD Screen

C H A P T E R 1

Hardware

the WD90C26 manages its frame buffer differently than QuickDraw expects, Pangola must perform byte packing and unpacking to support color modes other than 8-bit.

For example, in 1-bit mode QuickDraw expects that each byte in the frame buffer represents eight pixels. For every byte QuickDraw writes to the frame buffer in 1-bit mode, Pangola unpacks the bits and sends 8 bytes to the WD90C26. Similarly, Pangola must pack 8 bytes into 1 byte each time QuickDraw reads a byte from the frame buffer in 1-bit mode.

Because the WD90C26 is optimized for 8-bit color mode, there is little advantage to selecting a reduced bit depth. Apple recommends that application developers use 8-bit mode whenever possible on the Macintosh PowerBook 165c.

Applications that manipulate the frame buffer directly must do so at a consistent bit depth because Pangola always interprets pixel data based on the current video mode. For example, attempting to write 8-bit data to the frame buffer while in 1-bit mode will corrupt the frame buffer because Pangola will unpack each byte as described above. Sending 1-bit data to the buffer while in 8-bit mode produces similar results because Pangola will not perform the necessary conversion.

LCD Screen

The PowerBook 165c uses a high-contrast 640 x 400 pixel FSTN color display with .30 mm dot pitch. The display is backlit by two CCFL bulbs located at the top and bottom of the panel.

The inherent differences between LCD and CRT technologies make it a challenge to precisely match colors displayed on the LCD with those on an external monitor. The PowerBook 165c gamma table provides good color matching while minimizing flicker. Developers should use the supplied gamma table unless there is a specific need to replace it. Using a gamma table developed for RGB systems will produce poor results.

RAM Expansion Interface

The PowerBook 165c accommodates RAM expansion cards from 2 MB to 10 MB in capacity, for a total of 14 MB RAM. The RAM expansion interface is electrically identical to that of the PowerBook 180. However, the design of the PowerBook 165c provides more physical space for RAM expansion cards than was specified for earlier PowerBook computers, making it easier for developers to design high capacity cards.

The RAM expansion slot is located on the RAM/ROM board, in the same position as earlier PowerBook models. Figure 1-4 shows the location of the RAM expansion connector. Figure 1-5 shows the mechanical design guide for PowerBook 165c

RAM expansion cards. Refer to the Macintosh PowerBook 160 and Macintosh PowerBook 180 Developer Note for electrical design guidelines.

10 RAM Expansion Interface