USB Compatibility Issues

The following sections describe compatibility issues regarding legacy I/O (ADB and serial ports) as well as new functionality of the USB port.

ADB Compatibility

Apple is providing an ADB/USB shim to support processes that control ADB devices by making calls to the ADB Manager and the Cursor Device Manager. The ADB/USB shim makes it possible for processes that support an ADB keyboard to work with the USB keyboard equivalent.

Note

The iBook does not support the power-on key on the Apple USB keyboard.

Keyboards other than the Apple USB keyboard can be used with the iBook, but they will be treated as having an ADB device ID of 2.

IMPORTANT

The ADB/USB shim does not support USB devices other than the keyboard and mouse.

Note

The ADB/USB shim is built into the Mac OS ROM image on the iBook and on other Macintosh computers that have USB ports. For more information about the Mac OS ROM image, refer to Software

Serial Port Compatibility

The latest release of the Mac OS USB DDK includes a universal Serial/USB shim that allows processes that use the Communications Toolbox CRM to find and use a USB modem device. The shim is called SerialShimLib and is available as part of the Mac OS 8.6 release. For more information about the shim, and a sample modem driver that shows how to use it, please refer to the Mac OS USB DDK, available from the Apple Developer Development Kits page on the World Wide Web, at

http://developer.apple.com/sdk/index.html

Apple also provides a USB Communication Class driver, so modem vendors whose devices comply with the USB Communication Class specification do not need to write their own vendor-specific USB class drivers. See USB Drivers.

Power Off During Sleep

The USB port can be completely powered down during Sleep mode. USB devices must be able to start up again when the computer wakes up from Sleep mode. This functionality is part of the USB-suspend mode defined in the USB specification. Information about the operation of USB-suspend mode on Macintosh computers is included in the Mac OS USB DDK API Reference .

Macintosh-To-Macintosh Connections

USB is a serial communications channel, but it does not replace LocalTalk functionality on Macintosh computers; you cannot connect two Macintosh computers together using the USB. The best method for networking iBook computers is through the built-in Ethernet port.

USB Storage Devices

The Macintosh USB software supports booting from an external USB storage device.

Class drivers are software components that are able to communicate with many USB devices of a particular kind. If the appropriate class driver is present, any number of compliant devices can be plugged in and start working immediately without the need to install additional software. The Mac OS for the iBook includes USB Mass Storage Support 1.3, a class driver that supports devices that meet the USB Mass Storage Class specification. See USB Drivers.

USB Controller

The iBook uses an Open Host Controller Interface (OHCI) controller for USB communication. Some early USB devices (most notably keyboards) can't interoperate with an OHCI controller. Those devices are not supported by the Macintosh USB system software.