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minated SCSI-bus will cause malfunctions of the connected devices and data transfer
problems. The ICP Controller for this example has three independent SCSI channels: A, B,
C. In our example, two SCSI hard disks are connected to channel A (DR1, DR2), one to
channel B (DR3) and two to channel C (DR4, DR5). Our connection scheme is:
GDT-Channel A
DR1
DR2
GDT-Channel B
DR3
GDT-Channel C
DR4
DR5
We make sure that all three channels have a proper SCSI bus termination. The SCSI-IDs are
set according to the following list:
GDT channel A
ID 7 (default)
DR1
ID 0
DR2
ID 6
GDT channel B
ID 7 (default)
DR3
ID 2
GDT channel C
ID 7 (default)
DR4
ID 2
DR5
ID 4
Also three SCSI-cables are needed. The cables for channel A and C have three connectors,
where the cable for channel B has four, of which two connectors are used by a hard disk and
a CD-ROM drive which are not relevant for our example.
Please note: bad SCSI-cables, wrong SCSI-IDs as well as a wrong termination of the
busses are responsible for 95% of all possible errors !
In addition, it is essential that the hard disks and the controller be connected to the SCSI-
cable with the right orientation. Although SCSI-cables are keyed, you should cross-check if
all connectors of the cable have been pressed matching the correct key, especially when
using home-made cables.
We recommend terminating the SCSI-cables at their ends opposite to the controller by
means of so-called external terminator packs. These packs receive their terminator power
directly from the cable. In this case, the termination is to be removed from or disabled on
all hard disks. In order to get the best signal quality on the cable, the external terminator
packs should have an active SCSI termination. Advantage:
If you use the termination of a
hard disk and this hard disk happens to fail in a manner that harms the bus termination,
then it may occur that all devices connected to this cable do not function properly. There-
fore, it is sensible to use external terminators for reasons of redundancy.
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You can load GDTSETUP in two ways:
1.
Press the <CTRL><G> key combination when the GDT BIOS message comes up (shortly
after switching on the computer) and load GDTSETUP from the Flash-RAM of the ICP
Controller. In this case no operating system is required.
If GDTSETUP was loaded this way, there is an "R" (ROM) behind the version number.
2.
Load GDTSETUP from disk under MS-DOS. Boot the MS-DOS-operating system (either
from a boot-floppy or from an already existing boot drive, i.e., IDE-hard disk etc.). In or-
der for GDTSETUP to work properly, you have to load the device driver GDTX000 first.