Date: Thu, 18 Sep 1997 18:25:48 -0700 From: Don Lewis <Don.Lewis@tsc.tdk.com> To: Matthew Jacob <mjacob@feral.com>, Don.Lewis@tsc.tdk.com Cc: freebsd-hardware@FreeBSD.ORG, freebsd-scsi@FreeBSD.ORG Subject: Warning! Sun archaeology [was Re: Is my NCR controller broken?] Message-ID: <199709190125.SAA00739@salsa.gv.tsc.tdk.com> In-Reply-To: Matthew Jacob <mjacob@feral.com> "Re: Is my NCR controller broken?" (Sep 18, 5:25pm)
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On Sep 18, 5:25pm, Matthew Jacob wrote: } Subject: Re: Is my NCR controller broken? } >(this stuff predates SCSI 1) } } Wrong. I may have misremembered on this point. } > I believe the some Sun 3's actually } } Wrong. It was actually the sun 4/110. Looks like we're both right. I was unaware that the 4/110 was similarly afflicted. From my sun-managers archives: First, I was reminded about something which, while not directly impacting my situation, is well worth repeating. This is the infamous design decision(?) by Sun to ground the "termination power" SCSI pin on the 3/60 and 4/110 models, which means that a straight-through cable from either of these models to a SCSI drive with termination power supplied tends to blow the drive up! So while it's safe to plug an ex sun-3 drive onto a new system, plugging a new drive onto a 3/60 is potentially a problem! It's ok if you disable "termination power" on the drive, or cut the appropriate pin of the SCSI cable. Also >> 1) most Sun-2/Sun-3 SCSI cards don't supply termination power to the >> TRMPWR line on the SCSI bus. Only very late engineering rev >> cards supply power (if your's does it will have a fuse on >> the card). Make sure that your disk is supplying termination >> power (most disks have a jumper to enable/disable this). and from comp.periphs.scsi: The SparcStation 1 and 1+, Sun3/50 and 3/60, all do not supply term power. And, I think I recall that some 3/60s even have their TERMPWR pin (pin 26) wired to ground. This can cause serious smoke if you connect a device that sources term power; The 386i seems to be the only Sun (non-VME) that sources term power, as this was required to power the external terminator plug that was supplied with that machine. and from comp.periphs: Some time ago, there was much discussion of how Sun screwed up the SCSI interface on their 3/60s -- pin 26, which is supposed to supply +5 volts for termination power was grounded. This meant that any other device which chose to supply +5 on that line was likely to melt-down its power supply, or worse, its firmware. Since, up till now, I have always connected to Sun shoeboxes, I have not been concerned with this problem. However, now that I am connecting to another vendor's shoebox, I must take precautions. As a simple, if ugly, fix, I just cut wire 26 of the ribbon cable at the Sun end, causing line to float. (Actually, I made a short piece of cable with line 26 cut which I can insert between the sun and the cable to the disk drives). Strangely, when I tested for continuity between pin 26 and ground on the 3/60, there was none. Still, better to be safe... } I'd also like to point out that neither SCSI-1 nor SASI before } it specified cable pinouts- just pin numbers. } }-- End of excerpt from Matthew Jacob --- Truck
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