Technical information

CHAPTER 2
Architecture
Main Logic Board 25
on the main logic board. The Grackle IC also contains the controller for the
main memory.
The main memory bus runs at a clock speed of 66.67 MHz. The internal PCI bus
runs at 33.33 MHz. To enhance performance, the Grackle IC supports
concurrent transactions on the main memory bus and the PCI bus.
Information about the Grackle IC is available on the World Wide Web at
http://www.mot.com/SPS/PowerPC/products/semiconductor/
support_chips/106.html
Main Logic Board 2
All the I/O interfaces, the video and display subsystem, the expansion bay, and
the CardBus slot are on the main logic board. The modem is on a small card
connected to the main logic board. The controller ICs on the main logic board
are connected to the PCI bus.
I/O Controller IC 2
The I/O controller IC is an ASIC called Paddington. The Paddington IC is an
integrated I/O controller and DMA engine for use in Power Macintosh
computers that have a PCI bus.
The Paddington IC contains the PCI bus arbiter. It also provides the interface
and control signals for
■ the video display subsystem
■ the built-in modem
■ the infrared link
■ the Ethernet PHYTER IC
■ the sound interface IC
■ the internal EIDE hard drive
■ a drive in the expansion bay
■ the power manager IC