CHAPTER 3
Devices and Ports
Infrared Communication Link 35
Infrared Communication Link 3The iMac computer has a direct infrared (IR) communication link connected
internally to serial port B. When the computer is placed within range of another
device with an IR interface, it can send and receive serial data using the IrDA
protocol. The other device can be an IrDA-equipped Macintosh PowerBook or
some other device that complies with the Infrared Data Association (IrDA)
standard. The minimum range of the IR link is approximately 2 inches, and the
maximum range is 1 meter.
The IR link in the iMac computer supports IrDA at up to 4.0 Mbps. The IrDA
modulation method complies with the IrDA physical layer standard, which can
be found at ftp://irda.org.
Sound System 3The 16-bit stereo audio circuitry provides high-quality sound input and output
through the built-in microphone and speakers. The user can also connect
external input and output devices by way of the sound input and output jacks.
The sound system is based on the Burgundy codec IC along with input and
output ampliļ¬ers and signal conditioners. The sound system supports sample
sizes up to 16 bits at a sample rate of 44.1 kHz.
Table 3-2 Display resolutions and pixel depths
Resolution Vertical rate Pixel depth
(2 MB SGRAM) Pixel depth
(4 or 6 MB SGRAM)
640 by 480 117.233 Hz 32 bits 32 bits
800 by 600 94.97 Hz 32 bits 32 bits
1024 by 768 75.03 Hz 16 bits 32 bits