IBM Dock I, User Manual

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Pin I/O Signal Pin I/O Signal
15 N/A GND 40 O RST
16 I/O SCSIDATA (7) 41 N/A GND
17 N/A GND 42 I MSG
18 I/O SCSI PARITY 43 N/A GND
19 N/A GND 44 I/O SEL
20 N/A GND 45 N/A GND
21 N/A GND 46 I/O C/D
22 N/A GND 47 N/A GND
23 N/A GND 48 O REQ
24 N/A GND 49 N/A GND
25 (Open) 50 I/O I/O
Termination
The SCSI controller specification defines cable and termination
requirements as listed below.
The Dock I has an active termination. Observe the following rules
to use SCSI devices.
Internal SCSI device: Always terminate.
External SCSI devices: Terminate only the last SCSI device.
All SCSI buses require termination. The following guidelines must
be followed to ensure proper operation of the SCSI bus and SCSI
controllers.
Two terminations must be present on the bus. More than two
terminations may damage the SCSI controller or option devices,
or compromise data integrity. Make sure that the terminators
are in place on the end device on either side of the SCSI bus (a
total of two only).
The SCSI controller provides termination power (TERMPWR) to
the SCSI bus on Pin 26 of the internal and external SCSI
connectors. TERMPWR is protected by a thermal self-resetting
fuse located on the SCSI controller.
SCSI Cable Length Specifications
The Dock I SCSI controller specification for the SCSI cable length
connected to each SCSI interface is three meters (approximately 10
B-4
IBM ThinkPad Dock I User’s Guide
Title: C74AMST CreationDate: 06/23/93 17:09:07