Kurzweil Music Systems K2500R, K2500, K2500X Reference Guide

MIDI, SCSI, and Sample Dumps

SCSI Guidelines

Chapter 10 MIDI, SCSI, and Sample Dumps

SCSI Guidelines

The following sections contain information on using SCSI with the K2500, as well as speciﬁc sections dealing with the Mac and the K2500.

Disk Size Restrictions

The K2500 accepts hard disks with up to 2 gigabytes of storage capacity. If you attach an unformatted disk that is larger than 2 gigabytes, the K2500 will still be able to format it, but only as a 2 gigabyte disk. If you attach a formatted disk larger than 2 gigabytes, the K2500 will not be able to work with it; you could reformat the disk, but this - of course - would erase the disk entirely.

Conﬁguring a SCSI Chain

Here are some basic guidelines to follow when conﬁguring a SCSI chain:

1. According to the SCSI Speciﬁcation, 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.

2. The ﬁrst and last device in the chain must be terminated.

The K2500 comes with SCSI termination enabled. You must disable this termination if the K2500 will be in the middle of a SCSI chain or if you are installing a hard drive into the K2500.

There are three ways to disable the K2500’s termination, depending on the manufacture date of the unit. Newer K2500’s have an external "SCSI Termination Enable/Disable" switch on the rear panel. Older K2500’s require either the removal of SCSI termination resistors or a jumper setting; these modiﬁcations can only be performed by an authorized service center.

Poor termination is a common cause of SCSI problems. 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 K2500R, if it is not located at one end of a SCSI chain all internal termination, including the terminator resistor network on the K2500 Engine Board plus terminator resistors in the internal SCSI drive must be removed. It is much simpler to just make sure that the K2500 is at one end of the SCSI chain.

For a K2500 keyboard model, it must be at the end of the SCSI chain if it has an internal disk drive.

A note about active termination - The K2500 uses active termination of the SCSI bus. Active termination has some beneﬁts 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

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MIDI, SCSI, and Sample Dumps

SCSI Guidelines

all APS SR2000 series external drives use internal active termination that can be switched on or off.

3. Each device in the chain (including internal hard drives) must have its own unique SCSI ID. The default K2500 ID is #6. Macintoshes use ID #7 & #0.

4. 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 (800233-7550) 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.

5. You should buy all SCSI cables from a single source to avoid impedance mismatch between cables.

6. Theoretically all eight SCSI IDs can be used. However, feedback from users has shown us that many people have problems with more than 5-6 devices in a chain. If you have 7 or 8 devices and are having problems, your best bet is to make sure you have followed all of the previous information, especially with respect to cables.

7. Connect all SCSI cables before turning on the power on any equipment connected by SCSI cables. Plugging or unplugging SCSI cables while devices are powered on can cause damage to your devices or instrument.

8. Authorized service centers should remove termination from the K2500 when installing an internal drive, set its ID correctly, and terminate the drive.

9. When using a Macintosh, power up the K2500 and other devices ﬁrst.

10. The K2500 ﬁle format is a proprietary format; no other device will be able to read or write a Kurzweil ﬁle.

11. The ﬂoppy disk format of the K2500 is DOS. The SCSI disk format is a proprietary form that is close to DOS, but it is not DOS. Nonetheless, the K2500 can read and write to a DOS formatted disk provided it was formatted on the PC with no partitions.

12. It is possible to view, copy, move, name, delete ﬁles on a K2500 formatted ﬂoppy disk or removable media hard drive, with a PC or Macintosh running a DOS mounting utility program such as Access PC.

13. As long as the SCSI bus is properly terminated there is no way you can damage your hardware simply by operating it. There are a few hazards K2500 users should be aware of, however:

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The only damage that usually occurs to SCSI hardware comes from static electricity "zapping" SCSI connector pins when the cables are disconnected. The silver colored shell of the SCSI connector on the end of the cable is connected to ground and is safe to touch, but the brass colored pins inside eventually lead to the SCSI interface chip and are vulnerable. You should discharge static from your body before touching SCSI connectors by touching the 1/4" jacks on the rear of the K2500 or another grounded metal object. Any devices connected to the SCSI bus should be turned off when plugging or unplugging SCSI cables.

If the K2500 is connected to a Macintosh or PC you should make sure that the computer cannot access a SCSI disk at the same time the K2500 does (see below for more information on this). Those who occasionally want to share a drive, but don't want to take any risks would be best served by disconnecting and connecting devices as needed. If you want to share drive(s) often and cannot constantly disconnect and reconnect devices, make sure the Mac or PC is really done with the disk before using the K2500. Furthermore, you should quit or exit from all running programs and disable screen savers, email, network ﬁle sharing, and any INITs or TSR's that run in the background. If the computer and K2500 access the disk at the same time there will be no damage to the hardware, but the bits on the disk, K2500, and computer memory can easily be corrupted. You may not know that damage has been done to these bits until weird things start to happen for no apparent reason.

K2500 and Macintosh Computers

1. The Mac really does not like having another SCSI master on the bus (i.e., the K2500). It assumes that it owns the bus and its drives, therefore it will not tolerate the situation where the K2500 is trying to talk to its (the Mac's) disk. This suggests that you never want to select the ID of any drive mounted on the Mac's desktop. Even more fundamental is the problem that the Mac assumes that the bus is always free, so if it tries to do anything via SCSI when the K2500 is doing anything via SCSI, the Mac will freak. The only solution is, wait until your Mac is completely idle before accessing SCSI from the K2500.

MIDI, SCSI, and Sample Dumps

SCSI Guidelines

2. The Mac and the K2500 cannot share a drive in any way, with or without partitions. If you are using a drive with removable media, you cannot easily switch back and forth between a Mac formatted volume and a K2500 formatted volume. To prevent problems, you will need to unmount the drive from the Mac desktop before switching to a K2500 format volume. The Mac will basically ignore the volume if it's not Mac format, but once you insert a Mac format volume, the Mac owns it. Don't forget about #1 above; inserting a cartridge will cause the Mac to access SCSI, so don't try to use the K2K at that moment.

3. The only good reason for connecting the Mac and the K2K on the same SCSI bus is to use Alchemy or equivalent. If you're using a patch editor or librarian, you can just hook up via MIDI. Connecting via SCSI will allow fast sample transfers through the SMDI protocol. In this type of conﬁguration the easiest solution is to let the K2K have its own drive, and the Mac have it's own drive.

However, we have discovered that when using a K2500 with a Mac and a removable media drive in the middle of the chain, the following scenario will work:

Start with a Mac formatted cartridge in the drive. When you want to use the K2500, put the drive to sleep from the K2500. You can then change to a K2500 formatted cartridge and perform whatever disk operations you need. When you want to go back to the Mac, put the drive to sleep again, switch cartridges, and then wake up the disk by pressing Load . Of course the K2500 will tell you it can't read the cart, but the Mac will now access it ﬁne.

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