Detailed hardware description
Issue G
103
IDE interface
The APOLLO provides a single IDE channel capable of Ultra ATA 100 operation. This is
listed as the primary IDE interface in the BIOS. The primary IDE interface can support
several types of data transfers:
•
Programmed I/O (PIO): Processor is in control of the data transfer.
•
8237 style DMA: DMA protocol that resembles the DMA on the ISA bus, although it
does not use the 8237 in the ICH4. This protocol off loads the processor from moving
data. This allows higher transfer rate of up to 16MB/s.
•
Ultra ATA/33: DMA protocol that redefines signals on the IDE cable to allow both host
and target throttling of data and transfer rates of up to 33MB/s.
•
Ultra ATA/66: DMA protocol that redefines signals on the IDE cable to allow both host
and target throttling of data and transfer rates of up to 66MB/s.
•
Ultra ATA/100: DMA protocol that redefines signals on the IDE cable to allow both
host and target throttling of data and transfer rates of up to 100MB/s.
The primary IDE interface is made available to the user through a 2.54mm (0.1
"
) pitch pin
header. For connector details, see page
To improve signal integrity an 80-way IDE cable with 40-way connectors should
be used with devices supporting Ultra ATA/66 and above.
USB host controller
The USB host controller on the ICH4 provides support for six USB 2.0 compliant ports. USB 2.0
allows for a maximum data rate of 480Mbps and is downwardly compatible with the USB 1.1
specification. EHCI (version 2.0) and UHCI (version 1.1) are both supported by the USB ports.
A power switching circuit provides over current feedback to the system and current
limiting to 500mA per channel.
There are four signal lines associated with USB channels:
•
VBUS
•
DATA-
•
DATA+
•
GND
Their arrangement is summarized in the following illustration:
1
2
3
4
1
2
3
4
1
2
10 (GND)
(KEY) 9
VBUS
GND
VBUS 2
DATA+
GND
USB Connector 1
USB Connector 2
J18
DATA-
DATA+
DATA-