The GEMINI 020\030 (version V2.xx) is equipped with a high-speed SCSI (pronounced "scuzzy") interface which includes built-in SCSI termination. A SCSI Terminator is not the latest Arnold Schwartzenwhozitz sci-fi movie, nor is it a sleazy hit man.
The SCSI network uses "open-collector logic". Terminating resistors are required to bring the signals on an SCSI network to their correct inactive levels.
If the SCSI network has multiple devices, or if the total cable length exceeds 3 feet, it requires two sets of SCSI termination resistors. If two sets are used, there should be one at either end of the network. The GEMINI board provides one set of termination resistors at the head end of the SCSI network.
NEVER use more than two sets of SCSI termination resistors!!! Doing so will cause damage to the SCSI network and loss of data integrity.
Most SCSI devices are shipped with terminating resistor packs that can be removed or bypassed. Some devices are shipped without terminating resistors. These devices usually require an external in-line terminator. If your SCSI network has more than two devices with termination, and you have no method for disabling the termination, contact the manufacturer of the SCSI device for a solution.
SCSI Hard Drive Compatibility Issues
If you use a hard drive with your accelerated Macintosh, it is strongly recommended that you make a back-up of the contents of your drive, reformat the hard drive, reinstall the driver software, reinstall your System files, and then restore the contents of your drive. This will insure that your drive's performance with the GEMINI's high-speed SCSI interface is not restricted due to fragmented files slowing down drive access.
There are a number of SCSI hard drives that may no longer work correctly when connected to an accelerated Macintosh with the high-speed SCSI interface. In most cases, the problem can be corrected by reinstalling the drivers for your particular hard drive. However, it is possible that this MAY NOT provide an adequate solution to intermittent drive related performance problems.
Most SCSI hard drive problems are driver software related. We have successfully solved 90% of these problems by replacing the drive manufacturer's driver software with the drivers in LaCie's "SilverLining", Apollyonics Software Development's "SCSI Director Pro", or UniMac's "StorWare". We strongly recommend that if you are experiencing problems with your hard drive, use "SilverLining", "SCSI Director Pro" or "StorWare" to install new drivers on your hard drive.
The following is a list of hard drives with which we have experienced compatibility problems:
• Jasmine drives (all) -- many problems with Jasmine's DriveWare. Use Silverlining, SCSI Director Pro, or StorWare.
• Jasmine BackPac™ drives -- problems with older BackPacs with Rodime 45M and 100M drives. MAY be corrected with SilverLining, SCSI Director Pro, or StorWare.
• SuperMac XP series -- problems with SuperMac drivers and Copy ROM-to-RAM. Use SilverLining, SCSI Director Pro, or StorWare.
• MacBottom drives (by PCPC) -- problems with MacBottom driver software. Use SilverLining, SCSI Director Pro, or StorWare.
• Mirror M80 -- problems with Mirror driver software. Use SilverLining, SCSI Director Pro, or StorWare.
• Rodime 45 and 70 Mbyte -- severe compatibility problems. MAY be corrected with SilverLining, SCSI Director Pro, or StorWare.
• Western Digital drives -- not compatible.
• Any drive with OMTI or Adaptec SCSI controllers -- not compatible.
• Apple HD-20 (non-SCSI) -- not a reliable startup drive. Upgrade drive to SCSI. An accelerator-compatible SCSI upgrade for the Apple HD-20 is available from PCPC (1-800-MAC-BUTT -- seriously !).