NH82801DB S L8DE Intel, NH82801DB S L8DE Datasheet - Page 32

• Manufacturer Part Number: NH82801DB S L8DE
• Manufacturer: Intel

Specifications of NH82801DB S L8DE

• Lead Free Status / RoHS Status: Compliant

Introduction
32
Compatibility Modules (DMA Controller, Timer/Counters, Interrupt
Controller)
The DMA controller incorporates the logic of two 82C37 DMA controllers, with seven
independently programmable channels. Channels 0–3 are hardwired to 8-bit, count-by-byte
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
(APIC).
Universal Serial Bus (USB) Controller
The ICH4 contains an Enhanced Host Controller Interface (EHCI) compliant host controller 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
F1 and F2)
and
Section 5.17, “USB EHCI Controller (D29:F7)
Section 5.16, “USB UHCI Controllers (D29:F0,
for details.
Intel
®
82801DB ICH4 Datasheet