Motorola IH5 User Manual

Block Diagram

http://www.motorola.com/computer/literature

6-9

The MCPN750A uses the VIA Technologies VT82C586B Peripheral Bus 
Controller (PBC) to supply the interface between the PCI local bus and the 
ISA, EIDE and USB systems I/O bus (as shown in 

 on page 

).

The PBC controller provides the following functions:

❏

ISA (Industry Standard Architecture) bus arbitration for DMA 
devices (Note: feature not used since there are no ISADMA 
devices).

❏

EIDE Interface

❏

USB Interface

❏

Seven independently programmable DMA channels (Note: feature 
not used since there are no ISA DMA devices).

❏

Interrupt controller functionality to support 14 ISA interrupts

❏

Edge/level control for ISA interrupts

❏

Steerable PCI interrupts (Note: feature not used. Interrupt steering 
via Raven ASIC).

❏

Three interval counters/timers (82C54 functionality)

Accesses to the configuration space for the PBC are performed by way of 
the CONADD and CONDAT (Configuration Address and Data) registers 
in the Raven bridge controller ASIC. The registers are located at offsets 
$CF8 and $CFC, respectively, from the PCI I/O base address.

The PBC provides an ISA bus compatible interface. The ISA interface 
provides programmable timing and chip selects for ISA compatible 
peripherals. The ISA bus is used to interface to the serial port’s 
NVRAM/RTC chip and various board status registers.