Chapter 2. System-Board Features
(one-half the microprocessor bus). The ISA bus operates at 8.25 MHz (one-quarter of the PCI bus speed)
with a 66 MHz microprocessor bus.
For the ISA bus, no resource assignments are given in the system memory or the DMA channels. For
information on resource assignments, see “Input/Output Address Map” on page 41 and Figure 48 on
page 45 (for IRQ assignments).
USB Interface
Universal serial bus (USB) technology is a standard feature of the computer. Using the chip set, the
system board provides the USB interface with two connectors. A USB-enabled device can attach to each
connector, and if that device is a hub, multiple peripherals can attach to the hub and be used by the
system. The USB connectors use Plug and Play technology for installed devices. The speed of the USB
is up to 12 MB/sec with a maximum of 127 peripherals.
Features provided by USB technology include:
Support for hot pluggable devices
Support for concurrent operation of multiple devices
Suitable for different device bandwidths
Support for up to five meters length from host to hub or from hub to hub
Guaranteed bandwidth and low latencies appropriate for specific devices
Wide range of packet sizes
Limited power to hubs
For information on the connector pin assignments for the USB interface, see “USB Connectors” on
page 32.
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Technical Information Manual