IBM Dock I User Manual
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.
requirements as listed below.
The Dock I has an active termination. Observe the following rules
to use SCSI devices.
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.
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).
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.
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
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