Joe_Luzzi.FULLERTON_CC@QMBRIDGE.CALSTATE.EDU (Joe Luzzi) (03/15/91)
Time: 10:24 AM
Date: 12/21/90
Subject: Re: Much about Quantums and
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>>First, the prodrives don't do low-level formats - they're already
>>formatted at 1-1 interleave and they have a disk-cache built onto the
>>controller (I think it's 32k big). Anyway, one doens't need to do
>>low-level formats on Quantum Prodrives. If you try, it comes right
>>back instantly saying "Success."
That's exactly what happened, Dave. When I tried to format the drive on My
IIgs, it came back instantly saying success, or that the drive was write
protected, or format failure. On my Mac, I think it actually did a low-level
format because it took a few minutes (this was using the supplied mac
utilities).
>>Make sure there is only ONE set of terminating resistors at each END of the
>>chain.
I'm sure I had only one set of terminators on each end of the chain.
>>Anyone who tells you quantum drives don't work on a // is full
>>of it - Apple brand drives are Quantum mechanisms!
That's why I just sent the Quantum 210 back, rather than argue with them
(MacAvenue).
>>What you *do* need to do is set the SCSI ID of the drive correctly.
Each of the drives have push buttons to set the SCSI ID and they were both
different, the Apple DMA SCSI card being SCSI ID 7.
I don't know why the quantum didn't work. I have a Rodime 140 Plus hooked up
to my Apple DMA SCSI card now and it works fine. The Rodime has an external
terminator and the SCSI cable is about 3-4 feet long. I then wanted more disk
space and ordered the Protege Quantum from MacAvenue. I remove the terminator
from the Rodime and connected up the Protege drive using a peripheral cable
from Apple that's about 4 feet long. The Protege drive would not work all
alone on the chain (computer to Protege only).
So, that's the story. I'm gonna try another Quantum from some other hard drive
company or maybe just get a Chinook drive (Connor based mechanism).
Thanks all for your input.
>>Dave Whitney
>>Microsoft
>>My own opinions. I wrote Z-Link and BinSCII.
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Joe M. Luzzi
Internet: Joe@CSU.FULLERTON.EDU
BITNET: LJMLUZZ@CALSTATE.EDU
GENIE : JM.LUZZI
AOL : JMLUZZI
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=phs172m@vaxc.cc.monash.edu.au (Stephen Harker) (03/16/91)
In article <9103150330.AA02173@apple.com>, Joe_Luzzi.FULLERTON_CC@QMBRIDGE.CALSTATE.EDU (Joe Luzzi) writes: > [a lot deleted] > > I don't know why the quantum didn't work. I have a Rodime 140 Plus hooked up > to my Apple DMA SCSI card now and it works fine. The Rodime has an external > terminator and the SCSI cable is about 3-4 feet long. I then wanted more disk > space and ordered the Protege Quantum from MacAvenue. I remove the terminator > from the Rodime and connected up the Protege drive using a peripheral cable > from Apple that's about 4 feet long. The Protege drive would not work all > alone on the chain (computer to Protege only). > > So, that's the story. I'm gonna try another Quantum from some other hard drive > company or maybe just get a Chinook drive (Connor based mechanism). One last comment, from previous reading of comp.periphs.scsi and past posts on this group (especially one crossposted by Thad Floryan in 1979) a lot of SCSI drives don't (or didn't) have their internal wiring correct. SCSI devices are supposed to be daisy chained. However a lot are not internally daisy chained. So you could have a what you think is a daisy chained setup (looking externally) but it is not. SCSI drives are supposed to Not like look like []--| |--[] []-----[] | | | | | | |_____| | | | = = Where [] represents the external 50 pin connectors and = represents the internal drive. Apparently if this is not correct there can be vastly increased noise in the system which can cause problems with daisy chained drives. -- Stephen Harker phs172m@vaxc.cc.monash.edu.au Monash University
toddpw@nntp-server.caltech.edu (Todd P. Whitesel) (03/16/91)
phs172m@vaxc.cc.monash.edu.au (Stephen Harker) writes: >SCSI drives are supposed to Not like >look like > []--| |--[] []-----[] > | | | > | | | > |_____| | > | | > = = Aw shucks. My HDI PowerDrive (quantum 105s mech.) does it the 'bad' way. I understand why there's more noise in the second configuration, though. Electrically, you're splitting the signal as it passes through the drive, and there will be reflections and other wave effects at high transmission rates, which manifest themselves in the form of noise. Todd Whitesel toddpw @ tybalt.caltech.edu
bbean@pro-grouch.cts.com (Bruce Bean) (03/18/91)
In-Reply-To: message from phs172m@vaxc.cc.monash.edu.au
Bunk........ I happen to be running 4 drives that the internal cable is
the "L" configuration on an Apple High Speed SCSI card. I have no "noise"
problem what so ever.......
B.Beanmarks@pro-shop.cts.com (System Administrator) (03/18/91)
In-Reply-To: message from toddpw@nntp-server.caltech.edu >>SCSI drives are supposed to Not like >>look like >> >> []--| |--[] []-----[] >> | | | >> | | | >> |_____| | >> | | >> = = > >Aw shucks. My HDI PowerDrive (quantum 105s mech.) does it the 'bad' way. > >I understand why there's more noise in the second configuration, though. >Electrically, you're splitting the signal as it passes through the drive, >and there will be reflections and other wave effects at high transmission >rates, which manifest themselves in the form of noise. > >Todd Whitesel >toddpw @ tybalt.caltech.edu Todd, It is most probable that the signal doesn't pass through your drive, but loops out to the other drive before it gets to the first. There shouldn't be any noise from this setup. []==|___|======[] | | | = More like this if you can see what I mean. If you open up your drive case you will see that the two plugs are directly connected, and only one lead runs to the drive. While you've got the drive case open look at the bottom of the drive itself and you will see the terminating resistors. They are right above the molex plug, unless your drive is not a self terminator.(Most Seagates, and Conner are. I'm not sure about Quantums) That might be a source of line noise, as feedback due to a bad resistor or not enough resistance inline. -- Mark ---- ProLine: marks@pro-shop UUCP: crash!pro-shop!marks Internet: marks@pro-shop.cts.com DARPA: crash!pro-shop!marks@nosc.mil
phs172m@vaxc.cc.monash.edu.au (Stephen Harker) (03/19/91)
In article <8067@crash.cts.com>, marks@pro-shop.cts.com (System Administrator) writes: > In-Reply-To: message from toddpw@nntp-server.caltech.edu > >>>SCSI drives are supposed to Not like >>>look like >>> >>> []--| |--[] []-----[] >>> | | | >>> | | | >>> |_____| | >>> | | >>> = = >> >>Aw shucks. My HDI PowerDrive (quantum 105s mech.) does it the 'bad' way. >> >>I understand why there's more noise in the second configuration, though. >>Electrically, you're splitting the signal as it passes through the drive, >>and there will be reflections and other wave effects at high transmission >>rates, which manifest themselves in the form of noise. > > Todd, > It is most probable that the signal doesn't pass through your drive, but > loops out to the other drive before it gets to the first. There shouldn't be > any noise from this setup. > > []==|___|======[] > | > | > | > = > > More like this if you can see what I mean. If you open up your drive case you > will see that the two plugs are directly connected, and only one lead runs to > the drive. While you've got the drive case open look at the bottom of the > drive itself and you will see the terminating resistors. They are right above > the molex plug, unless your drive is not a self terminator.(Most Seagates, > and Conner are. I'm not sure about Quantums) That might be a source of line > noise, as feedback due to a bad resistor or not enough resistance inline. Since the SCSI cable is functioning basically as a transmission line this is a possible source of noise, as you will get reflection from any lead which is taking signals off to the side. This is effectively connecting in parallel. How significant a noise problem is another matter - the major area this problem has been brought up is with people who are extending the SCSI bus near to its limits, ie 6m (20ft) of cable. When you reach this situation sub-standard cabling or connections will likely cause problems, but for most of us it is unlikely that we would notice any problems as the bus is not running anywhere near its limits, which is why most drive manufacturers that do this get away with it. However if you are serious about wanting low noise or a long cable run then it is best to stick with the daisy chained cabling. Also you should ensure that all cables are of the correct impedance, I believe that 100 ohms is recommended. If not you will get reflection when two cables of different impedance meet. The bottom line is that it won't matter in most cases, because the noise level will be too low to affect the system. But if you do have problems, especially with long cable runs, then this is an area to look at. -- Stephen Harker phs172m@vaxc.cc.monash.edu.au Monash University