Universal Serial Bus Connectors - IBM IntelliStation A Pro Type 6217 User Manual

v Domain name validation to negotiate compatible data-transfer speeds with each
v Cyclic-redundancy checking (CRC) to improve data reliability
v An active terminator for SCSI bus termination
The following illustration shows a SCSI connector.
SCSI cabling requirements
You can install four internal SCSI devices using the SCSI signal cable that comes
with some computer models. If you plan to attach external SCSI devices, you can
order an additional SCSI cable, remove the SCSI knockout from the rear of the
computer, and connect the new cable from the SCSI channel B connector on the
system board to this opening. To select and order the correct cables for use with
external devices, contact your IBM reseller or IBM marketing representative. See
"System-board internal connectors" on page 37 for the locations of the SCSI
connectors.
If you want to attach external SCSI devices to the computer without using the
internal SCSI channel B, you must install an optional SCSI adapter.
Setting SCSI IDs
Each SCSI device that is connected to a SCSI controller must have a unique SCSI
ID. This ID enables the SCSI controller to identify the device and ensure that
different devices on the same SCSI channel do not attempt to transfer data
simultaneously. SCSI devices that are connected to different SCSI channels can
have duplicate SCSI IDs. See the information that comes with the device for
instructions for setting its SCSI ID.

Universal Serial Bus connectors

There are five Universal Serial Bus (USB) 2.0 connectors, two on the front and
three on the rear of the computer. Use the USB connectors to connect optional
telephony and multimedia devices. USB 2.0 technology transfers data at up to 480
Mb per second (Mbps) with a maximum of 127 external devices and a maximum
signal distance of 5 meters (16 ft) per segment (if the device that is attached to the
computer is a USB 2.0 device). If multiple USB devices are attached to the
computer, the USB hub must be USB 2.0; otherwise, all USB 2.0 devices will
transfer data at 12 Mbps. Using Plug and Play technology, USB devices are
configured automatically. The following illustration shows a USB connector.
Use a 4-pin USB cable to connect an external devices to a USB connector.
If you connect a PS/2 (non-USB) keyboard to the keyboard connector, USB ports
and devices are disabled during power-on self-test (POST).
If you connect a USB keyboard that has a mouse port, the keyboard emulates a
mouse, and you cannot disable the mouse settings in the Configuration/Setup Utility
program.
device
34
68
1 4
1
35
Chapter 4. Installing options
69