shankar@SRC.Honeywell.COM (Subash Shankar) (05/03/91)
Here's another of my weekly (or so it seems) problem postings, this time concerned with a problem I was having with my SCSI card and hard drive. I turn on the GS like usual (SCSI card in slot 7, one Quantum daisy chained off one Syquest, termination only on the Quantum). Instead of the thermometer display, I'm greeted with the red light on my hard drive flashing at a regular interval, and system fails to boot. Suspecting a hard drive crash, I remove the Quantum from the chain, and attempt to boot with the Syquest, with no luck. Since this problem has occurred off and on over the last two weeks (but always fixable by turning everything off and back on), I suspect bad connections on the SCSI card, and clean the fingers on the (Rev. C) SCSI card and the slot, push hard on all the sockets, and try to boot the Quantum (again at the end of the daisy chain) with no luck. Next, I check the connectivity of the ribbon cable on my SCSI card with a multimeter, and everything checks out OK. The card goes back in the computer, but the boot fails again. Finally, I throw up my hands for about a week, and then assemble the whole system again, and things fail again. But then, I boot the SCSI utilities disk that came with the SCSI card and it sees all SCSI partitions (Copy II+ failed to see any of the partitions a week earlier). Then, I change the control panel back to booting from slot 7, and this time everything works perfectly. Some of this is probably extraneous, but I didn't want to leave anything out. Does anybody have any suggestions as to what's wrong with my system? --- Subash Shankar Honeywell Systems & Research Center MN65-2100 voice: (612) 782 7558 US Snail: 3660 Technology Dr., Minneapolis, MN 55418 shankar@src.honeywell.com srcsip!shankar
mattd@Apple.COM (Matt Deatherage) (05/04/91)
I'll bet you have termination problems sometimes. When using a Rev. C Card, you need a terminator on the first and last device (or one terminator if you only have one device). When using a High-Speed card, you need a terminator at the end of the chain (or no terminators if you only have one device). -- ============================================================================ Matt Deatherage, Developer Technical | The opinions expressed herein are Support, Apple Computer, Inc. | not those of Apple Computer, and Personal mail only, please. Thanks. | shame on you for thinking otherwise. ============================================================================
philip@utstat.uucp (Philip McDunnough) (05/04/91)
In article <52411@apple.Apple.COM> mattd@Apple.COM (Matt Deatherage) writes: >When using a High-Speed card, you need a terminator at the end of the chain >(or no terminators if you only have one device). Hmm...what if you have only one device( a hard drive) and you use a terminator with the High-Speed card? Can it harm anything? Philip McDunnough University of Toronto philip@utstat.utoronto.ca [my opinions,etc...]
mattd@Apple.COM (Matt Deatherage) (05/04/91)
In article <1991May4.015842.11339@utstat.uucp> philip@utstat.uucp (Philip McDunnough) writes: >In article <52411@apple.Apple.COM> mattd@Apple.COM (Matt Deatherage) writes: > >>When using a High-Speed card, you need a terminator at the end of the chain >>(or no terminators if you only have one device). > >Hmm...what if you have only one device( a hard drive) and you use a >terminator with the High-Speed card? Can it harm anything? > >Philip McDunnough Hmm. Honestly? I don't know. My gut says "don't do it," though. -- ============================================================================ Matt Deatherage, Developer Technical | The opinions expressed herein are Support, Apple Computer, Inc. | not those of Apple Computer, and Personal mail only, please. Thanks. | shame on you for thinking otherwise. ============================================================================
alfter@nevada.edu (SCOTT ALFTER) (05/05/91)
In article <1991May4.015842.11339@utstat.uucp> philip@utstat.uucp (Philip McDunnough) writes: >In article <52411@apple.Apple.COM> mattd@Apple.COM (Matt Deatherage) writes: >>When using a High-Speed card, you need a terminator at the end of the chain >>(or no terminators if you only have one device). >Hmm...what if you have only one device( a hard drive) and you use a >terminator with the High-Speed card? Can it harm anything? Depends on whether your HD is internally terminated. Most SCSI mechanisms are terminated at the factory; the people who turn these bare mechanisms into finished drives with cases, connectors, etc. usually remove these terminator packs from the mechanisms. If you built your own drive (like I did), you shouldn't need to add another terminator as the HD's terminator packs hold down one end of the chain while the DMA SCSI card holds down the other end. If you bought a finished drive (from Chinook, QC, or someone like that), you'll need to stick a terminator on one of the drive's connectors. Scott Alfter-----------------------------_/_---------------------------- Call the Skunk Works BBS (702) 896-2676 / v \ 6 PM-6 AM PT 300/1200/2400 Internet: alfter@uns-helios.nevada.edu ( ( Apple II: GEnie: S.ALFTER \_^_/ the power to be your best!
philip@utstat.uucp (Philip McDunnough) (05/05/91)
In article <52437@apple.Apple.COM> mattd@Apple.COM (Matt Deatherage) writes: >In article <1991May4.015842.11339@utstat.uucp> philip@utstat.uucp (Philip McDunnough) writes: >>In article <52411@apple.Apple.COM> mattd@Apple.COM (Matt Deatherage) writes: >> >>>When using a High-Speed card, you need a terminator at the end of the chain >>>(or no terminators if you only have one device). >> >>Hmm...what if you have only one device( a hard drive) and you use a >>terminator with the High-Speed card? Can it harm anything? >> >>Philip McDunnough > >Hmm. Honestly? I don't know. My gut says "don't do it," though. Sorry to belabor the point but this is rather unsettling. It was my impression, and is in virtually every HD/SCSI card manual, that you needed 2 terminators in a SCSI chain. Usually one at the beginning and the other typically, though not necessarily, placed at the end. The Rev C SCSI card has no terminator, while the High-Speed one is rumoured to have one[ I own a High-Speed one]. That would seem to imply that you would need 2 terminators with the Rev C card, and only one with the High-Speed card. I have been using a SCSI HD with a ROM03 and one terminator since day one. Nothing has ever happened to the hard drive, but I doubt that my TWGS has enjoyed the trip to Texas so many times. Is there a definitive word on this? I have received so many different replies since reading MD's message( replies from dealers, friends, colleagues,etc..) re whether or not to remove that terminator that it's become kind of funny. Philip McDunnough University of Toronto [my opinions,etc...]
toddpw@nntp-server.caltech.edu (Todd P. Whitesel) (05/05/91)
philip@utstat.uucp (Philip McDunnough) writes: >needed 2 terminators in a SCSI chain. Usually one at the beginning >and the other typically, though not necessarily, placed at the end. The Word: No more than two. One is OK if there are only two devices and a single short cable, but two are always better. Terminators should always be AT the end of the chain if at all possible. >The Rev C SCSI card has no terminator, while the High-Speed one is >rumoured to have one[ I own a High-Speed one]. The High Speed SCSI does in fact have termination built in to the card. You can see it in the form of three thin yellow things (9 pins each) sticking up next to where the cable is soldered to the card (argh, should have been socketed). Todd Whitesel toddpw @ tybalt.caltech.edu
daveh@ccwf.cc.utexas.edu (Dave Huang) (05/06/91)
In article <52411@apple.Apple.COM> mattd@Apple.COM (Matt Deatherage) writes: >When using a High-Speed card, you need a terminator at the end of the chain >(or no terminators if you only have one device). Is this for the Apple SCSI card only, or for all SCSIs in general? I had always thought that the SCSI bus had to be terminated at both ends. Since all SCSI cards for the IIs have a terminator on the card (is that right??), I thought that you'd need a terminator at the end of the other device (like a HD). -- David Huang | Internet: daveh@ccwf.cc.utexas.edu | "One with a face made of metal UUCP: ...!ut-emx!ccwf.cc.utexas.edu!daveh | should not use the word 'rust'" America Online: DrWho29 |
mattd@Apple.COM (Matt Deatherage) (05/06/91)
In article <48477@ut-emx.uucp> daveh@ccwf.cc.utexas.edu (Dave Huang) writes: >In article <52411@apple.Apple.COM> mattd@Apple.COM (Matt Deatherage) writes: > >>When using a High-Speed card, you need a terminator at the end of the chain >>(or no terminators if you only have one device). > >Is this for the Apple SCSI card only, or for all SCSIs in general? I Sorry, I thought my capitalization implied that I was speaking only of the Apple products (the rev. C card and the High-Speed card). I can't and won't speak for other SCSI cards because I have no clues about their workings. -- ============================================================================ Matt Deatherage, Developer Technical | The opinions expressed herein are Support, Apple Computer, Inc. | not those of Apple Computer, and Personal mail only, please. Thanks. | shame on you for thinking otherwise. ============================================================================
philip@utstat.uucp (Philip McDunnough) (05/06/91)
In article <52478@apple.Apple.COM> mattd@Apple.COM (Matt Deatherage) writes: >In article <48477@ut-emx.uucp> daveh@ccwf.cc.utexas.edu (Dave Huang) writes: >>In article <52411@apple.Apple.COM> mattd@Apple.COM (Matt Deatherage) writes: >> >>>When using a High-Speed card, you need a terminator at the end of the chain >>>(or no terminators if you only have one device). >> >>Is this for the Apple SCSI card only, or for all SCSIs in general? I > >Sorry, I thought my capitalization implied that I was speaking only of the >Apple products (the rev. C card and the High-Speed card). I can't and won't >speak for other SCSI cards because I have no clues about their workings. >============================================================================ >Matt Deatherage, Developer Technical | The opinions expressed herein are >Support, Apple Computer, Inc. | not those of Apple Computer, and >Personal mail only, please. Thanks. | shame on you for thinking otherwise. >============================================================================ Well I am also speaking only of Apple products as well. Since there appears to be some confusion here, perhaps we should clarify the setup. ROM03, High-Speed(Apple) SCSI card and a hard drive that is NOT internally terminated. Now, Todd has indicated that one should not use more than 2 terminators and that the High-Speed SCSI card has a built in terminator. So, does the High-Speed card have a built in terminator? Assuming it does, and that there is only one hard drive connected to it( which is not internally terminated) are you saying that one should not put a terminator( or need not) on the hard drive? Now the Rev C card does not have a terminator, so why shouldn't one need 2 terminators? Bottom line: should I remove the terminator from my drive or not!? Philip McDunnough University of Toronto [my opinions,...]
toddpw@nntp-server.caltech.edu (Todd P. Whitesel) (05/06/91)
philip@utstat.uucp (Philip McDunnough) writes: >Now the Rev C card does not have a terminator, so why >shouldn't one need 2 terminators? You _would_ need 2 terminators. A terminator at each end of the chain is the recommended (and often required) setup for things to work reliably. It is usually possible to get away with a single terminator on single cable SCSI chains, but I would recommend against it. >Bottom line: should I remove the terminator from my drive or not!? No. It's just fine where it is. Your chain has a terminator on each end -- one on the H.S. SCSI card, and the other on the drive. Bottom line: If it works, don't fix it. Todd Whitesel toddpw @ tybalt.caltech.edu
mattd@Apple.COM (Matt Deatherage) (05/06/91)
In article <1991May6.010943.5215@utstat.uucp> philip@utstat.uucp (Philip McDunnough) writes: > >Bottom line: should I remove the terminator from my drive or not!? > >Philip McDunnough >University of Toronto >[my opinions,...] Yes. I said this before, I still mean it. I do not know the answers to your other questions and said so, and repeating them will not jog my memory. -- ============================================================================ Matt Deatherage, Developer Technical | The opinions expressed herein are Support, Apple Computer, Inc. | not those of Apple Computer, and Personal mail only, please. Thanks. | shame on you for thinking otherwise. ============================================================================
toddpw@nntp-server.caltech.edu (Todd P. Whitesel) (05/06/91)
Arrgghh, I hate to do this. No hard feelings, Matt; I'm also glad to see you back on the net. mattd@Apple.COM (Matt Deatherage) writes: >philip@utstat.uucp (Philip McDunnough) writes: >>Bottom line: should I remove the terminator from my drive or not!? >Yes. I said this before, I still mean it. Matt, he said that his drive doesn't have internal termination -- if he removes it, one end of the cable won't be terminated at all. Sure, it will probably still work, but the SCSI spec explicitly states that both ends should be terminated. Todd Whitesel toddpw @ tybalt.caltech.edu
daveh@ccwf.cc.utexas.edu (Dave Huang) (05/07/91)
In article <52478@apple.Apple.COM> mattd@Apple.COM (Matt Deatherage) writes: >Sorry, I thought my capitalization implied that I was speaking only of the >Apple products (the rev. C card and the High-Speed card). I can't and won't >speak for other SCSI cards because I have no clues about their workings. I understood that you were speaking of the Apple card, but I was just wondering if this applied to other cards. My question wasn't specifically directed to you... Glad to see that you're reading/posting again :-) >============================================================================ >Matt Deatherage, Developer Technical | The opinions expressed herein are >Support, Apple Computer, Inc. | not those of Apple Computer, and >Personal mail only, please. Thanks. | shame on you for thinking otherwise. >============================================================================ -- David Huang | Internet: daveh@ccwf.cc.utexas.edu | "One with a face made of metal UUCP: ...!ut-emx!ccwf.cc.utexas.edu!daveh | should not use the word 'rust'" America Online: DrWho29 |
mattd@Apple.COM (Matt Deatherage) (05/07/91)
In article <1991May6.081109.14843@nntp-server.caltech.edu> toddpw@nntp-server.caltech.edu (Todd P. Whitesel) writes: >Matt, he said that his drive doesn't have internal termination -- if he >removes it, one end of the cable won't be terminated at all. Sure, >it will probably still work, but the SCSI spec explicitly states that >both ends should be terminated. > You see why I didn't want to answer this question? It turns into a holy way _every single time_. It's like potato chips - you can't answer it just once. Or, like happens here, someone (probably me) gets confused about the original question somewhere along the line, or people interpret a response for a specific situation as appropriate always, or...never mind. Let's just deal with it. There are four unique situations hinging on two boolean questions: 1) Do you have a Rev. C or a High Speed SCSI Card? (Non-Apple cards are NOT being discussed here.) 2) Do you have more than one SCSI device on your chain? (We will assume that all drives have no internal termination. If yours does, it counts a drive with a terminator.) The key points here are that the SCSI Specification says the bus should be terminated on both ends, but a) the High-Speed Card has a terminator on-board and the Rev. C card does not, and b) short chains or slow throughputs can often let you bend this slightly with no ill effects. So... IF YOU HAVE A REV. C CARD AND ONE SCSI DEVICE: You need one terminator. (Since the Spec says you need two and the card has none, you'd think you'd need to monkey with this somehow, but the SCSI chain is so short and the throughput slow enough that one terminator works just fine.) IF YOU HAVE A REV. C CARD AND MORE THAN ONE SCSI DEVICE: You need a terminator on the first device and a terminator on the last device (just like the Spec says). IF YOU HAVE A HIGH-SPEED SCSI CARD AND ONE SCSI DEVICE: You can use zero or one terminators. (Since the card is terminated, you should need a terminator on the device, according to the Spec, but the SCSI bus is usually so short that the lack of another terminator causes no problems. If you have a longer cable or if no terminator is not working, try adding one.) IF YOU HAVE A HIGH-SPEED SCSI CARD AND MORE THAN ONE SCSI DEVICE: You need one terminator on the last device. Adding more terminators could cause problems (the card is terminated). ------------------ Note that in all cases one of the SCSI devices must supply termination _power_, since for either SCSI card to do so would seriously overuse the specified power per slot in the system. Questions? Keep 'em to yourself. If anyone around you asks these questions, print this out and nail it to their forehead. Ten-penny nails work best. (yes, that last paragraph was a joke.) -- ============================================================================ Matt Deatherage, Developer Technical | The opinions expressed herein are Support, Apple Computer, Inc. | not those of Apple Computer, and Personal mail only, please. Thanks. | shame on you for thinking otherwise. ============================================================================
RANKINS@gecrdvm1.crd.ge.com (05/07/91)
I have a Rev C SCSI card and a drive case with a hard drive and a tape drive in it. The tape drive is at the end of the chain and internally terminat terminated. From what you are saying, the cable should be terminated at the SCSI card end as well? Where would I find such a terminator (25 pin male on one side, 25 pin female on the other so it could go between the card connector and the cable)?
gwyn@smoke.brl.mil (Doug Gwyn) (05/08/91)
In article <1991May6.010943.5215@utstat.uucp> philip@utstat.uucp (Philip McDunnough) writes: >Bottom line: should I remove the terminator from my drive or not!? We've been through this before, so to simply summarize BRIEFLY: Electrically, there should be termination at both ends of the SCSI bus and nowhere in the middle of the bus. The "Rev C" SCSI Card did not provide termination; the "High-Speed SCSI Card" does provide termination. There was thus no ideal way to configure the Rev C SCSI subsystem, and Apple's recommendation was to put one terminator at the big end of the "Apple SCSI System Cable", which was as close to the Rev C Card as one could install an Apple SCSI terminator. In the case of only one device other than the SCSI interface attached to the SCSI bus, e.g. a single HD20SC, following that recommendation would put a single terminator at what happened to already be the "far" end of the bus, hardly ideal, but better than the alternatives. For "Rev C" subsystems with more than one SCSI peripheral, Apple recommended a second terminator at the far end of the bus (in addition to the one somewhat near the Rev C SCSI Card). The High-Speed (DMA) SCSI Card eliminates this nonsense, because it includes termination at its end of the SCSI bus, so regardless of the peripheral complement attached to a High-Speed SCSI subsystem, one adds just one terminator at the far end of the SCSI bus, always. (In all these descriptions I have assumed the devices are not supplying termination. Once one determines where the terminator(s) SHOULD be, then if there is a device plugged in at that spot one can use the drive's internal SCSI bus termination, if it provides it (normally a couple of flat resistor packs). Termination should be removed from all devices that are not being deliberately configured with termination to satisfy the "both ends terminated" SCSI bus requirement.)
whitewolf@gnh-starport.cts.com (Tae Song) (05/09/91)
|Well I am also speaking only of Apple products as well. Since there |appears to be some confusion here, perhaps we should clarify the |setup. ROM03, High-Speed(Apple) SCSI card and a hard drive that is |NOT internally terminated. Now, Todd has indicated that one should |not use more than 2 terminators and that the High-Speed SCSI card |has a built in terminator. So, does the High-Speed card have a built |in terminator? Assuming it does, and that there is only one hard |drive connected to it( which is not internally terminated) are you |saying that one should not put a terminator( or need not) on the |hard drive? Now the Rev C card does not have a terminator, so why |shouldn't one need 2 terminators? | |Bottom line: should I remove the terminator from my drive or not!? | |Philip McDunnough |University of Toronto |[my opinions,...] Bottom line: It doesn't matter. Why, because you only 1 drive. When you have multiple drives, then you DO need a terminator. The terminator helps cut noise and cross talking. But in the interest of enforcing the stanard just leave it on, if it works. Like they say if it isn't broken don't fix it. Rev C... well, I think they were terminated... but not properly. INET: whitewolf@gnh-starport.cts.com UUCP: crash!gnh-starport!whitewolf ARPA: crash!gnh-starport!whitewolf@nosc.mil
lhaider@pro-nbs.cts.com (Laer Haider) (05/10/91)
In-Reply-To: message from toddpw@nntp-server.caltech.edu
>Bottom line: If it works, don't fix it.
Coming from a programmer? How may programs have you made, Todd, that
worked; that you couldn't stop yourself from fixing? <grin>
Actually, in the context you were using that phrase, it's ok. But, such
an attitude applied too widely stagnates improvements or advances in just
about anything it's applied to.
I like to think: If it works, that's great! How can I make it work BETTER.
/ _______________________________________________
\ / / ProLine: pro-nbs!lhaider
\\\' , / // INET: lhaider@pro-nbs.cts.com
\\\//, _/ //, UUCP: crash!pro-nbs!lhaider
\_-//' / //<, ARPA: crash!pro-nbs!lhaider@nosc.mil
\ /// <//` BITNET: lhaider%pro-nbs.cts.com@nosc.mil
/ >> \\\`__/_
/,)-^>>\` , \\\ The opinions express here are just opinions.
(/ \\ /\\\ Don't have a cow man!
// _//\\\\ -----------------------------------------------
((` ((