Path: news1.icaen!news.uiowa.edu!news.physics.uiowa.edu!math.ohio-state.edu!howland.erols.net!cam-news-hub1.bbnplanet.com!news.bbnplanet.com!news.maxwell.syr.edu!news.bc.net!unixg.ubc.ca!freenet.vancouver.bc.ca!not-for-mail From: gareth@vcn.bc.ca (Gareth Jones) Newsgroups: comp.sys.apple2 Subject: Re: Zip drive not working with High-Speed SCSI. Help! Date: 20 Feb 1997 16:20:31 GMT Organization: Vancouver CommunityNet Lines: 62 Distribution: world Message-ID: <5ehtkf$iq2@milo.vcn.bc.ca> References: <5e0ds0$252a@usenetw1.news.prodigy.com> <5e49nu$b4p@dove.qut.edu.au> <5eaejk$1dh4@usenet1y.prodigy.net> NNTP-Posting-Host: opus.vcn.bc.ca X-Newsreader: TIN [UNIX 1.3 BETA-950824-16colors PL0] ToasterKing (toastjuice@aol.com) wrote: : hard drive to the end of the SCSI chain. I've heard there is a simple : modification I can do to my HS SCSI card to make it supply termination : power. It requires soldering a jumper wire from a +5V source on the card : (or anywhere in the GS, for that matter) to one of the SCSI pins. If : anyone has seen this mod or could tell me which SCSI pin to solder the : jumper to, I'd appreciate it if you'd let me know. : : : Thanks!! : You can find the picture of the mod on http://ground.isca.uiowa.edu/apple2 somewhere (in the documentation folder, I believe). It has a name something like HS.SCSI.GIF, although that may not be exactly right. The following article from _Apples B.C. News_ will supplement, not replace, the GIF. -Gareth Apple II Cafˇ (October 96): Modifying Your Apple II High Speed SCSI Card to Supply Termination Power. Al Crout For a SCSI system to work properly, termination power must be supplied by one device in the SCSI chain. With a minor modification, the Apple II High Speed SCSI card can be adapted to supply termination power. Supposing you have just purchased a new, larger (bigger, better, faster) hard drive thinking: "At last, I can get rid of all these small drives I have accumulated!". However, after a few hours of preparation, you discover that your new hard drive is not recognized by system software unless...one of your old drives is part of the SCSI chain. AAARRGH! According the the High Speed SCSI Card Owners Guide, the problem is:"A drive won't work by itself but it will work when connected to another drive" and the solution is: "The hard drive may not supply termination power, in which case it can never be used alone...". Well, the manual fails to mention that the High Speed SCSI card is itself a SCSI device and it, too, fails to supply termination power. You can easily verify the problem by connecting your new drive to a friend's Sequential Systems RAMfast SCSI card, which does supply termination power, and observing how well your new drive works on its own. Modifying the Apple II card is easy and inexpensive. In fact, a diagram of the mod was recently circulating in one of the Apple II internet newsgroups and should be easily obtained (it's also available from our IIGS disk library). After carefully removing the SCSI card from your Apple II and familiarizing yourself with the diagram and the main components of the SCSI card, all that is necessary is to obtain a 1N914 diode (readily available from an electronic parts store), clip its leads and solder it to two points on the back of the High Speed SCSI card while observing the normal precautions when dealing with heat-sensitive components like diodes, IC's and fingers. Re-inserting your High Speed SCSI card and reassembling your SCSI system should give you the desired results: your new hard drive should now be recognized on its own by the system software. By the way, you may find a gizmo called the "SCSI Sniffer" helpful in diagnosing SCSI problems. The SCSI Sniffer attaches to the end of the SCSI chain, providing termination. The feature that sets it apart from other terminators is the addition of seven LEDs (Light Emitting Diodes) which indicate various SCSI activities including, termination power, I/O, ACK, REQ, etc. The MAC Station, in Maple Ridge, sells this item at a discounted price.