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Surviving SCSI Hell

The Poetics of SCSI for Musicians and Samplists

Musicians often refer to a journey through SCSI Hell when they are setting up their samplers. This is a deliberately simple article dealing with a technical subject area. We're not here to become SCSI experts but simply to get our sampler connected to our computer. I'm including links in case you desire to learn more about SCSI, but all the basics are on this page.

 Fortunately, its not as bad as it used to be as samplers, particularly Emu samplers, which have much better, more robust scsi hooks built into the operating systems than they did a few years ago.  Originally, the idea was simply to connect samplers to CD Rom players so the user could load (and buy) sample cd roms.  However, it quickly became apparent that users also wanted to use their computers to edit, store, and manipulate samples.  This requires not only a connection between sampler and cd rom, but for the PC to recognize and control the sampler's innards and the sampler to shut up and listen when the PC says to do something.  Also, they have to "share" devices like cd roms, cdr machines, hard disks, etc., and in order for this to happen, the scsi masters must be able to "refresh" their memory of what is the current state of these fickle peripherals.  And both the computer and the sampler needs not to "freak out" (i.e., crash) when the drive that was there a moment ago is no longer there because the "other" master temporarily borrowed, or "stole" it.

Three "Core" Concepts of SCSI: IDs, termination, and refresh.

ID's. 

Typically, there are 8 SCSI IDs on a given scsi adapter (card), and there can be only one device on each ID. One of them, typically #7, is reserved for the "host adapter" or SCSI card that fits into a slot inside your computer.  Consider the IDs like TV channels.  If you want to watch a certain show, you have to tune in to the right channel.  To send a sample to a sampler, the computer will send the appropriate data down to cable to the ID it thinks the sampler is on.  If the sampler is on the right channel, its will sense the data coming in and respond by receiving it.  If its set to a different channel (ID), it will ignore the data.  Easy so far.  The tricky part is this.  Some devices insist on using certain IDs.  Most PC SCSI cards want ID# 7.  Most Zip drives give you a choice of 5 or 6.  CD Rom drives and hard drives fortunately are pretty flexible and you can assign any ID.  But the trick to these devices is that you can't just take them out of the box an plug them in.  You have to manually set the ID with tiny little "jumpers" that typically reside on the back of the drive.  (Some drives have tiny switches in a row called "dip switches".  The same concept applies.)  You have to actually read the manual to figure out which jumper setting corresponds to which ID. But don't let this scare you.  It's pig-easy to set jumpers, all you have to do is read a simple diagram and stick the little plastic jumper over the right pins. Also, let me tell you now.  Never throw away your manual to a SCSI device.  Keep it where you will find it in two years when you decide to change your SCSI setup.  The ID assignment does not have to follow any order.  You don't have to assign IDs the way you cable up items, nor do IDs have to be in sequential order.  They just have to be unique, where only one device "owns" a certain ID.

For more on ID's and SCSI arbitration (a fancy word for which device gets the data), check out the Adaptec Hardware FAQ.  Great info! 

Termination 

OK, you got the IDs set.  Now you need to tell the master where the "end" of the scsi chain is.  We are not talking about the "logical" end, which would be the last ID, but the physical end(s), the last device(s) physically on the chain(s). There may be one or two chains.  One is the external chain from the outside port on the scsi card.  The other in the internal chain, connected from the card's internal SCSI port.  Typically, samplers should be put at the end of the external chain, because often they only have one connector, so you can't connect beyond that.  Termination tells the Master device that the end of the chain is reached so it can stop sending commands.  If termination is not set, when the master does not receive the acknowledgment from the last device, it might simply wait for it.  It might eventually "time out" after waiting a specified period, or yep, it might wait forever for the response that never comes, and your system will essentially be "locked up".  Most samplers are "auto terminating" which means they sense when they are the last device and act appropriately.  Internal CD ROM devices are usually not so smart, and you have to turn the termination "on" on the last device.  Termination is set on most devices by either a jumper or a dip switch, much like IDs. Again this is easy.  Just look for the termination diagram in the manual and do the jumper thing again. There's no soldering, wires, or mess.  Just stick the little plastic jumper, a small rectangular plastic piece with two holes, over the correct pins.  You can do it by hand alone, though sometimes a needle nose pliers helps pull them out them from their current locations, or put the girlfriend's fingernails to work. 

To clarify lets say your system starts with the scsi card in the computer (ID7) then one path goes to the external out of the card to a ZIP, then to a Hard drive (ID2) and cd rom drive (ID4)  in an external case, then to the sampler. (ID5).  However the other thread goes from the Internal connector on the scsi card to a CDRW internal to the computer (ID3).  Which devices need to be terminated?  Answer:  Both the Sampler and the Internal CDRW machine as these are the two physical ends of the chains.  If you want more info on SCSI termination in a more technical (and accurate) language go to Adaptec's termination page.

Refresh

  When you change a SCSI ID to a device like a sampler, the changes often don't take place until you cycle the power.  On some particularly errant scsi systems, you might have to actually unplug the device from the wall and power back on before the device will assume its new identity.  Rule of thumb when changing IDs and termination.  Power down, wait a minute, and cold start everything afterwards.  A "warm boot" might not do it.  Failure to do this has led has led to many a samplist pulling out their hair.  If your SCSI system ever completely goes bonkers on you, its a good idea to power down, make some coffee, let you and your system refresh yourselves.

Also, most samplers have a command to poll the SCSI pathways to see which devices are connected.  This situation may change often when you swap out zip disks or remove, replace a cdrom disc from the drive.  By hitting the "Re-log drives" command in the sampler, the sampler will get a fresh picture of everything that is connected.  Its a great idea to relog your drives after your computer accesses a device you want your sampler to access.  Windows, for example will constantly re-log all scsi drives connected to see if new media has been inserted.  This "feature" wreaks havoc on samplers as Windows often "steals" the device away from the control of the sampler.  The trick here is to go to the Windows control panel and turn "auto insert notification" OFF, and leave it off, never turn it back on, and if any program (like the real audio jukebox) asks you if it can turn it on for you  always say NO!  The PC has no business accessing the samplers drives.  It can't read them, and because it can't read them, it assumes they are blank and that you might want to format them.  The answer there is, of course, NO!.  Moral of the story, on the PC, turn off "Auto insert notification"  You Don't want the PC to relog the drives.  From the sampler side, you DO want to relog the the drives.  Consider the PC to be a bully, its always trying to take more drives than it owns.  The Sampler is a wimp, its constantly losing its drives to the PC, so it has to constantly reclaim them.  This is why you have to turn auto insert off--so the PC behaves. 

Cables and Connections

Zip drives are easy because they have 2 connectors, so they are perfect for the middle of the chain.  Internal CDRs and CD Roms are good too, because SCSI ribbon a cable like you see in a computer can connect many different devices.  Devices that will cause trouble are external CD Rom/R machines that

have one connector.  Which are you going to connect it to?  If you connect it to the one scsi port on the sampler then how do you get to the PC?  The work around here is 1) Simply, do not get an external unit that has one SCSI port, make sure it has two.  2) Buy a SCSI ribbon cable with multiple connectors like is used inside the computer can buy some external connectors and attach them to the cable.  Its not recommended by manufacturers, but it works and its cheap.        

Are you using the correct cables and adapters?   Before you buy a CDR machine make sure you physically look at the connector to see what kind it is, noting whether it is male or female.  You do not need the "best" scsi cables to get your sampler working reliably, no matter what the documentation says in your manual.  I routinely only buy the cheapest, and they have never, ever, caused me a problem. DO make sure your cables are securely connected.  Use the clips and fasteners to make sure the connection is tight.  And if you are having problems with data transfers take a look back there and make sure the cable didn't get unseated partially.  Its very wise to cut the power before messing with your cable connections. 

Here's everything you need to know about the many different types of connectors.  At the bottom of this page is a place where you can buy cables and connectors.  As you see, it is a good idea to avoid devices with the newer 68 pin connectors as they are pricey!  The "old" "Mac style" 25 pin and old "scsi 1" 50 pin stuff works well and are the least expensive.  Your sampler will not know the difference. 

I'm still in SCSI Hell, Help!

Sometimes you do all the above and there still is a problem.  Perhaps SoundForge will not see your sampler.  Sometimes your computer locks up when it polls the sampler at boot.  Solutions may not exist for some problems and scsi cards, particularly the ultra cheap scsi cards that may have come bundled with cdr drives.  However, if you have an Adaptec card of recent origin, you should be able to get it to work.

1. Recheck termination.  It's a pain, I know, but you have to do this.  Pull the cd roms out of the computer and check the jumpers.  Make sure those internal cables are tight.  These are usually the problem when you crash during boot.  See, Windows is waiting for the last SCSI device to yell back "I'm the last dude on the chain, go ahead".  But because you didn't set termination to on the the last device, possibly a cd rom drive deep in the computer, windows doesn't hear it and is waiting. Or the cable is out of the slot so the command never got to the terminating device.  OK tweaks, listen.  95% of the problems I have helped people with were due to this.  

2. Recheck scsi IDs and auto insert notification on the cd drives.  You are sure?  Ok proceed.

3. Go to the Device manager and see if the scsi card is in the list.  If not, the Plug N Play driver is not installed.  If yes, but there is an (!) exclamation mark, the driver is not installed properly.  Sometimes this may happen if you install the wrong driver, or if you installed the driver with incorrect ID settings, even if you later corrected them.  Another possibility is that your SCSI driver is installed with DOS drivers and is operating in Real Mode.  If your SCSI card has its own BIOS, which will show on the screen at bootup time, it may need to be tweaked to work in windows better. Some cards may have a control panel you can access from windows.  Some cards may allow you do disable the SCSI bios and that might help. 

Having a BIOS enabled allows your computer to boot from a SCSI hard drive.  If you are only using SCSI hard drives from the sampler, and using SMDI to bounce samples around, and accessing scsi cd roms from both the sampler and computer, then the BIOS may not need to be enabled.  You'll have to consult the manufacturers site or your manual for more specifics.  Sometimes SCSI card makers assume you only want to use SCSI hard Drives with your computer and think that's why you bought their product.  They might have you install a utility that makes this easy to do.  If the first thing you did after popping in the scsi card was to run an installation program from a cd rom, it may have installed some utilities and a real mode DOS driver. Sometimes these utilities completely confuse the new user and lead you down the wrong path.  They typically are not thinking you want to install a digital sampler and use SMDI.  I advise that you not use such utilities and don't even install them. Most cards only need the windows plug n play driver to be installed for full functionality of the sampler, cd drives, and SMDI. For more detailed info, read this article in the Microsoft knowledge base.

SCSI Setup & Basic SCSI Troubleshooting in Windows

Uninstall the driver(s) and installation programs.  Shut down.   Turn on all SCSI devices.  Now Boot.  Let windows find the SCSI card without any drivers installed and follow the prompts.  This will allow the "Plug N Play" features of windows to find the card, load drivers and register the driver in the registry.  The computer will probably ask you to reboot.  Do it.  Now see if the scsi card shows up.  Go to Sound Forge and see if it shows up there.  It should be there now. 

4. Know when to give up on a card. Sometimes you have to.  If your SCSI card is old and came out before PNP (plug N Play) when windows 95 became popular, you may have to do a ton of research to get it working right, and there is a possibility it will never work.  Some ISA and even some freebie PCI cards, even if installed and registered properly with windows, will fail during a SMDI dump.  These problems are usually related to bad drivers.  You might try to install a more current driver if one exists.  After that, you should weigh the the value of getting a new card that is known to work with your sampler.  You can leave hell at any time by spending 50 bucks on the right card.

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Best of Luck in your Music Making!

Rich the TweakMeister

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