Apple Desktop Computer manual USB Controller, Video Display Subsystem, Built-in Modem

C H A P T E R 2

Architecture

■the built-in modem

■the infrared link

■the Ethernet port

■the sound ASIC

■the internal IDE hard drive

■the internal CD-ROM drive

■the power manager IC

The Paddington IC is similar to the Heathrow IC used in the Power Macintosh G3 computers and Macintosh PowerBook G3 computers. The main difference is that the Paddington IC supports 100Base-TX Ethernet as well as 10Base-T.

USB Controller

The USB controller is a standard IC with two USB connectors. The register set complies with the Open Host Controller Interface (OHCI) specification.

Video Display Subsystem

The display subsystem consists of a graphics controller ASIC, 2 MB of SGRAM on the main logic board, and a connector for an additional 2 MB or 4 MB of SGRAM on an SO-DIMM. For information about the SGRAM SO-DIMM, see Chapter 4, “Expansion.”

The graphics controller IC is an ATI Rage IIc. It contains 2D and 3D acceleration engines, a digital video port, front-end and back-end scalers, a CRT controller, and a PCI bus interface with bus master capability.

For information about the display and supported resolutions, see Chapter 3, “Devices and Ports.”

Built-in Modem

The built-in hardware modem is a separate module that is connected to the SCC port A of the Paddington IC. The module contains a modem controller IC, a datapump, and the interface to the telephone line (DAA).

Main Logic Board 25