Power Video

While Microsoft touts the Memphis OS's support for four monitors once it's released, for 10 years the Mac OS has supported up to six monitors. When the Mac II was introduced, Color QuickDraw, the Mac's imaging engine, was designed to support multiple monitors with different pixel depths and resolutions. When you plugged a NuBus video board into the system, the Slot Manager automatically fetched the board's driver and hardware characteristics from its firmware. The Slot Manager passed this information to Color QuickDraw. The user didn't do anything other than arrange ho w the monitors displayed the desktop. The limitation of six monitors was due to the number of NuBus slots in the Mac II.

For PCI Macs, an Expansion Manager obtains board information for Color QuickDraw. The different bus interface necessitates this new Manager. Open Firmware obtains the board's driver, initializes it, and passes board characteristics back to the Mac OS. As before, no user intervention is necessary: You simply plug in the board and start the system. You use the Monitors and Sound Control Panel to arrange the orientation of the monitor screens.