HP Vectra VL 5/xxx 5 IDE Controller, USB Controller, DMA Controller, Counter / Timer, PCI Bus Interface, ISA Bus Interface, Interrupt Controller, PCI/ISA Bridge Chip (82371SB)

2 System Board

Chip-Set

	PCI/ISA Bridge Chip (82371SB)
	This chip is encapsulated in a 208 pin plastic quad flat pack (PQFP)
	package.
PCI Bus Interface	This part of the chip performs PCI-to-ISA, and ISA-to-PCI bus cycle
	translation. It supports the Plug-and-Play mechanism.
ISA Bus Interface	As well as accepting cycles from the PCI bus interface, and translating them
	for the ISA bus, the ISA bus interface also requests the PCI master bridge to
	generate PCI cycles on behalf of a DMA or ISA master. The ISA bus interface
	contains a standard ISA bus controller and data buffering logic. It can directly
	support six ISA slots without external data or address buffering.
IDE Controller	The PCI master/slave IDE controller, supporting four devices, two on each of
	two channels, is described on page 34.
USB Controller	The PCI USB controller, supporting two connectors, is described on page 36.
DMA Controller	The seven channel DMA controller incorporates the functionality of two
	82C37 DMA controllers. Channels 0 to 3 are for 8-bit DMA devices, while
	channels 5 to 7 are for 16-bit devices (see page 82). The channels can be
	programmed for any of the four transfer modes: the three active modes
	(single, demand, block), can perform three different types of transfer: read,
	write and verify. The address generation circuitry can only support a 24-bit
	address for DMA devices.
Interrupt Controller	The sixteen channel interrupt controller incorporates the functionality of
	two 82C59 interrupt controllers. The two controllers are cascaded, giving 14
	external and two internal interrupt sources (see page 82).
Counter / Timer	The chip contains a three-channel 82C54 counter/timer. The counters use a
	division of the 14.31818 MHz OSC input as the clock source.

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