Apple iMac - Manual (Page 31)

C H A P T E R 3
Devices and Ports
USB Ports 31
Serial Port Compatibility 3
The first release of the MacOS USB DDK does not include a universal Serial/
USB shim that would allow processes that use the Communications Toolbox
CRM to use a USB serial device. At the introduction of the iMac computer, any
USB Serial Class Driver will need to implement its own Serial/USB shim.
The first release of the Mac OS USB DDK does not include a universal Serial/
USB shim that would allow processes that use the Communications Toolbox
CRM to find and use a USB modem device. At the introduction of the iMac
computer, any USB modem device would need to implement its own
communication shim to interface between the CRM and its USB
Communication class driver. For more information, please refer to the Mac OS
USB DDK, which is available from the Apple Developer DDK page on the
World Wide Web, at
http://developer.apple.com/sdk/
Macintosh-To-Macintosh Connections 3
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 iMac
computers is through the built-in Ethernet port.
USB Storage Devices 3
The Macintosh USB software does not support booting from an external USB
storage device.
USB Controller 3
The iMac computer 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 will not be supported
by the Macintosh USB system software.