Midi And Scsi Sample Dumps; Scsi Guidelines - Kurzweil K2000 - MUSICIANS GUIDE Musician's Manual

Chapter 29

MIDI and SCSI Sample Dumps

SCSI Guidelines

The following sections contain information on using SCSI with the K2vx, as well as speciÞc
sections dealing with the Mac and the K2vx.
Here are some basic guidelines to follow when conÞguring a SCSI chain:
1.
2. The Þrst and last device in the chain must be terminated.
3.
4.
5.
According to the SCSI SpeciÞcation, the maximum SCSI cable length is 6 meters (19.69').
You should limit the total length of all SCSI cables connecting external SCSI devices with
Kurzweil products to 17 feet (5.2 meters). To calculate the total SCSI cable length one
must add up the lengths of all SCSI cables, plus 8" for every external SCSI device
connected. No single cable length in the chain should exceed 8 feet.
Poor termination is a common cause of SCSI problems. If you install an internal drive that
is terminated, the termination resistors should be removed from the K2vx Engine Board.
Having more than two terminators on the bus will overload the bus drivers, but this
should not cause permanent damage to the hardware. Poor termination can corrupt the
data on your disk, however, as can bad SCSI cables.
For the K2vxR, if it is not located at one end of a SCSI chain all internal termination,
including the terminator resistor network on the K2vx Engine Board plus terminator
resistors in the internal SCSI drive must be removed. It is much simpler to just make sure
that the K2vx is at one end of the SCSI chain.
A note about active termination - The K2vx uses active termination of the SCSI bus.
Active termination has some beneÞts over traditional passive termination. Some people
have positioned active termination as a panacea for SCSI problems, but this is more hype
than reality. Active terminators are available to be used at the end of one's SCSI chain and
all APS SR2000 series external drives use internal active termination that can be switched
on or off.
Each device in the chain (including internal hard drives) must have its own unique SCSI
ID. The default K2vx ID is #6. Macintoshes use ID #7 & #0.
Use only true SCSI cables - high quality, twisted pair, shielded SCSI cable. Do not use
RS432 or other non SCSI cables.
The majority of SCSI cables we've tested were poorly made and could damage data
transferred to and from the disk. Nearly all the SCSI data problems Young Chang's
engineering department has had have been due to bad cables that didn't twist pairs of
wires properly. Correctly made SCSI cables have one ground wire for every signal wire
and twist them together in signal/ground pairs. Cables made by APS Technologies (800-
233-7550) are very good and are highly recommended. Young Chang manufactures 1 and
2 meter 25-25 SCSI cables, that we can also recommend. Good cables are essential to
reliable data transfers to and from the disk drive.
One should buy all SCSI cables from a single source to avoid impedance mismatch
between cables.
MIDI and SCSI Sample Dumps
SCSI Guidelines
29-1