Fifth in a series of articles on how to have a successful relationship with your Mac.
I'm so happy! I finally got a removable hard drive AND a scanner! No more trying to organize a gazillion floppies. No more driving all over town to get a scan from a service bureau. OooooWeee!
You've probably heard the expression 'Plug 'n Play' when it comes to adding devices to the Mac. Buy a peripheral ... plug it in ... and play! Well, almost. First, you have to understand what a SCSI device is.
SCSI (Small Computer System Interface - pronounced SCUZY) is what gives us the ability to link SCSI devices together - called SCSI or daisy chaining. All Macs have at least one SCSI port plus an internal SCSI connection for a hard disk.
At present, a SCSI chain can contain a total of seven devices plus the Mac. Each item on the chain must have its own SCSI ID number (address) - numbered 0 to 6. The Mac is always SCSI ID 7 and if you have an internal hard disk, it will be numbered SCSI ID 0. All other devices in the chain (i.e. scanners, SyQuest drives, CD-ROMs etc.) must have their own unique SCSI ID number. If you accidentally give two devices the same number, the system will crash - not start up - and you could possibly wipe out data on your hard disk. You can assign a SCSI ID number by changing the number (usually found on the back of the device). Make sure you check the manual for specific information about your particular device.
For those of you that have the push-type buttons on the back - be careful that you don't accidentally change the number by accidentally pushing the small buttons when you move it around on your desk - or even turning it on or off. It's also a good idea to write the SCSI ID on a little round or square sticker and put it on the front of the device.
So, what happens when you have set up everything correct and you still can't access the device? Most times it's a simple matter of "Mounting" the device. You can do this with Mounting/Formatting Software. Hard Disk ToolKit by FWB is my favourite. SCSI Probe, SpotOn and ETC are some others.
What about cables? There are two kinds of connectors for SCSI - 25 pin and 50 pin - with configurations such as 25-pin male to 50-pin male, 25-pin male to 25-pin male. As well they come in varying lengths. The industry standard is the 50-pin - you will find the 25-pin connector on the back of the MAC - but almost everywhere else - the 50-pin.
The most common cable is 3 feet long, however you can buy 6 ft to 18 ft. cables. Be careful, however, because you cannot exceed a total 18 ft. of cable in a SCSI chain without problems.
Last, but certainly not least - The Terminator! This is a small piece of hardware that looks like the plug at the end of a cable - but without the cable. A terminator is required on the first and last device on the chain (don't include the Mac). This means the first and last device in the actual physical chain - not the ones with the lowest and highest SCSI ID. A rule of thumb is ... if a jack doesn't have a terminator in it, put one in! Beware of devices that come with internal termination - check your owner's manual for more information.
I've tried to keep it simple here for the sake of space - but if you run into trouble, get professional help and advice to avoid any serious problems.
So stay tuned to this column to learn more about your relationship with a Mac. Watch for these insightful articles: How to nurse a sick Mac back to health ... Care and Feeding of the Mac ... and more!
The Mac Lady is an independent web designer located in Vancouver, BC. Your comments and suggestions are always welcome and appreciated.
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