FIC MB05W Service Manual
FIC MB05 Service Manual
1-85
transfers, and channels 5
–
7 are hardwired to 16-bit, count-by-word transfers. Any two of the
seven DMA channels can be programmed to support fast Type-F transfers.
The ICH4 supports two types of DMA (LPC and PC/PCI). DMA via LPC is similar to ISA DMA.
LPC DMA and PC/PCI DMA use the ICH4
’
s DMA controller. The PC/PCI protocol allows PCI-
based peripherals to initiate DMA cycles by encoding requests and grants via two PC/PCI
REQ#/GNT# pairs.
LPC DMA is handled through the use of the LDRQ# lines from peripherals and special
encodings on LAD[3:0] from the host. Single, Demand, Verify, and Increment modes are
supported on the LPC interface. Channels 0
–
3 are 8 bit channels. Channels 5
–
7 are 16 bit
channels. Channel 4 is reserved as a generic bus master request.
The timer/counter block contains three counters that are equivalent in function to those found
in one 82C54 programmable interval timer. These three counters are combined to provide the
system timer function, and speaker tone. The 14.31818-MHz oscillator input provides the
clock source for these three counters.
The ICH4 provides an ISA-Compatible Programmable Interrupt Controller (PIC) that
incorporates the functionality of two 82C59 interrupt controllers. The two interrupt controllers
are cascaded so that 14 external and two internal interrupts are possible. In addition, the
ICH4 supports a serial interrupt scheme.
All of the registers in these modules can be read and restored. This is required to save and
restore system state after power has been removed and restored to the platform.
Advanced Programmable Interrupt Controller (APIC)
In addition to the standard ISA compatible Programmable Interrupt Controller (PIC) described
in the previous section, the ICH4 incorporates the Advanced Programmable Interrupt
Controller
Universal Serial Bus (USB) Controller
The ICH4 contains an Enhanced Host Controller Interface (EHCI) compliant host ontroller that
supports USB high-speed signaling. High-speed USB 2.0 allows data transfers up to 480
Mb/s which is 40 times faster than full-speed USB. The ICH4 also contains three Universal
Host Controller Interface (UHCI) controllers that support USB full-speed and low-speed
signaling.
The ICH4 supports 6 USB 2.0 ports. All six ports are high-speed, full-speed, and low-speed
capable. ICH4
’
s port-routing logic determines whether a USB port is controlled by one of the
UHCI controllers or by the EHCI controller. See Section 5.16,
“
USB UHCI Controllers (D29:F0,
F1 and F2) and Section 5.17,
“
USB EHCI Controller (D29:F7) for details.
LAN Controller
The ICH4
’
s integrated LAN Controller includes a 32-bit PCI controller that provides enhanced
scatter-gather bus mastering capabilities and enables the LAN Controller to perform high
speed data transfers over the PCI bus. Its bus master capabilities enable the component to
process high-level commands and perform multiple operations; this lowers processor
utilization by off-loading communication tasks from the processor. Two large transmit and
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