Apple powermac g3 blue.white Service Manual

 

 Troubleshooting

General/Architecture of the Main Logic Board - 2

 

The architecture of the main logic board is based on the PowerPC 

G3 microprocessor and these buses: the processor bus, two PCI 

buses, a primary 32-bit 66 MHz bus, and a secondary 64-bit 33 

MHz bus. The processor bus connects the microprocessor, cache, 

and main memory; the primary PCI bus is for an Apple graphics 

card solution; the secondary PCI bus connects the I/O devices. The 

I/O devices on the secondary PCI bus are:
• Ultra DMA/33 (ATA-4) disk interface
• USB interface
• FireWire interface
• Paddington I/O controller IC
• PCI 33.33 MHz 64-bit slots #2, #3, and #4
• DEC/Intel 21154 PCI-PCI bridge IC