hull@hao.UUCP (02/28/87)
In article <1111@ulowell.cs.ulowell.edu>, page@ulowell.cs.ulowell.edu (Bob Page) writes: > You should check other things. First is disk quality. Second is > proximity to the monitor degaussing circuits and other electromagnetic > fields - tipping the *amiga* up could bring it too close to these > circuits. Other suggestions: air flow (heat problems, dirt), > direct sunlight, etc. Holy Bit Map Batman! This never occurred to me, and I work with this stuff all the time. Ok. So how many times can one subject a floppy disk to monitor turn-on (Say, with the disk sitting on top of the monitor, fer instance) before the disk goes bits-up? Has anyone out there done an experiment with this? I don't want to re-invent the wheel, but it might be time to get out the gaussimeter... Although this has nothing to do with ionizing radiation, or even microwaves - I am reminded of the following: "There may in fact be no safe level for ionizing radiation. It could be that any amount does some damage. But due to diploidal genes, the human body has a much greater resistance to ionizing radiation than most of us realize. Usually, cells along the particle track just die outright. Other than that, minor damage is repaired as the cell reproduces by pairing protines in the manufacture of the needed DNA. But there is a very thin zone somewhere within the ion track where, due to multiple damage sites distributed along the gene, irreparable damage is done. Various functions of the cell are permanently altered, usually for the worse; where this puts a cell at a disadvantage, subsequent generations die out. If the replication control is damaged, it may give that cell an advantage over other others in it's reproduction, even though other functions may be impaired. Such cells are known as pre-malignant cells, and may do no harm until stress kills healthy cells and forces the damaged cells to reproduce. Then you get cancer. So the best advice is avoid unnecessary stress on the body as may be caused by cigarettes, alcohol, and other carcinogens - and stay away from ionizing radiation. All considered, it's just a matter of how long you'll last..." [Remembered from a conversation with Ed Martell.] Although smokers and non-smokers alike die of many of the same diseases, the average life span for smokers is less by something like ten years... Howard Hull [If yet unproven concepts are outlawed in the range of discussion... ...Then only the deranged will discuss yet unproven concepts] {ucbvax!hplabs | decvax!noao | mcvax!seismo | ihnp4!seismo} !hao!hull for domain mailers, hull@hao.ncar.edu
billk@crash.UUCP (03/01/87)
Now hold on! You monitor could hardly get much closer to the internal drive than it is while sitting on top of it! Does the Amiga monitor automatically deguass when turned on? (I guess it must...) Hmmmmm... I wouldn't think that this would be the cause of the trouble that my friend encountered. When the his Amiga CPU was tipped on edge, it systematically trashed any disk it wrote to with the internal drive! billk
grr@cbmvax.UUCP (03/01/87)
In article <560@hao.UCAR.EDU> hull@hao.UCAR.EDU (Howard Hull) writes: >In article <1111@ulowell.cs.ulowell.edu>, page@ulowell.cs.ulowell.edu (Bob Page) writes: >> You should check other things. First is disk quality. Second is >> proximity to the monitor degaussing circuits and other electromagnetic >> fields - tipping the *amiga* up could bring it too close to these >> circuits. Other suggestions: air flow (heat problems, dirt), >> direct sunlight, etc. > >Holy Bit Map Batman! This never occurred to me, and I work with this stuff >all the time. Ok. So how many times can one subject a floppy disk to >monitor turn-on (Say, with the disk sitting on top of the monitor, fer >instance) before the disk goes bits-up? Interesting, but not really the question here. What can happen is that the *magnetic* fields produced by the flyback transformer or the yoke in the monitor can induce currents in the heads or read/write circuitry of the floppy drive. This reduces the noise margins and can result in read errors. Write errors are improbable, but it is not hard to rewrite mis-read data and thus trash the disk. The simple way to check for this is to move the drive away from the monitor or interpose a piece of sheet *steel* between the monitor and the drive. As have been previously mentioned, the floppy should operate in any reasonable orientation. However, a drive that is worn out, out of alignment or otherwise not quite what it should be might well have a higher error rate when used in other than the "normal" orientation. -- George Robbins - now working for, uucp: {ihnp4|seismo|rutgers}!cbmvax!grr but no way officially representing arpa: cbmvax!grr@seismo.css.GOV Commodore, Engineering Department fone: 215-431-9255 (only by moonlite)
rico@oscvax.UUCP (03/02/87)
In article <560@hao.UCAR.EDU> hull@hao.UUCP writes: >> (Bob Page) writes: >> You should check other things. First is disk quality. Second is >> proximity to the monitor degaussing circuits and other electromagnetic >> fields - tipping the *amiga* up could bring it too close to these >> circuits. >Holy Bit Map Batman! This never occurred to me, and I work with this stuff >all the time. Ok. So how many times can one subject a floppy disk to >monitor turn-on (Say, with the disk sitting on top of the monitor, fer >instance) before the disk goes bits-up? Has anyone out there done an >experiment with this? Just the other day, I was trying to corrupt a Macintosh disk so that I could re-format it as single-sided. So I took the disk and but it in front of this big Hitachi monitor that I use and hit the DEGAUSS button, I held it there for a while with the button down until the screen stopped doing the funny things it does during degaussing, then waited for a while and repeated this several times. The net effect on the disk was.... nil. The Mac read the disk sans hitch. No files lost or anything. What does this tell me? The chance of accidentally wiping out a disk by exposure to a monitor's electro-magentic fields is virtually zero. But don't forget, I don't know what I'm talking about... -Rico -- [NSA food: terrorist, cryptography, DES, drugs, CIA, secret, decode] [CSIS food: supermailbox, tuna, fiberglass coffins, Mirabel, microfiche] [Cat food: Nine Lives, Cat Chow, Meow Mix, Crave]
frazier@cti.UUCP (03/02/87)
In article <853@crash.CTS.COM>, billk@pnet01.CTS.COM (Bill Kelly) writes: > > Hmmmmm... I wouldn't think that this would be the cause of the trouble that my > friend encountered. When the his Amiga CPU was tipped on edge, it > systematically trashed any disk it wrote to with the internal drive! > > billk For all of you people that don't (aparrently) read the manual and are guessing what might cause this problem of trashing discs: In the Amiga manual (Even the little one that is for the "first time computer user") there is a large bold printed announcement that you "SHOULD NOT STORE OR OTHERWISE HAVE A DISC WITHIN THREE FEET OF THE MONITOR WHEN THE SYSTEM IS TURNED ON", or words of similar impact. (I don't have the manuals here at work). Now, one may ask (and rightly so) just how you can get away with booting the system normally (IE: in a hurry like most of us do) without problems. Well, the monitor MAY not automatically degauss, and there is some shielding around the drive, and MANY of us have probably been breaking the "3 foot rule" from day one with no adverse effects (I know that I often do), but you never know if it's slowly wiping your discs until it's too late. On the other hand, the warning may just be something included to keep Commodore off the hook if you start losing disc data due to degaussing problems. No, it shouldn't make any difference whether the drive is on it's side or not, I've had one of my external floppies "on edge" for over a year without a problem, and have only trashed a few discs in that time (all have been in the internal drive, and a couple were the old "turn off power with the access light on problem" (a definite no-no on ANY computer). The only possible way that turning the amiga on it's side (end) should make would be if the bottom is closer to the monitor than the (normal) top, AND IF the shielding inside the Amiga is less effective on the bottom than that on the top. (Really grasping at straws now aren't we?) --rick -- DISCLAIMER: The foregoing is the result of a brain frazzled by the effects of insufficient sleep and a noisy phone line, and in no way reflects the opinion of my employer, friends, or enemies. I'm not even sure I really wrote it. UUCP: {decwrl,pyramid}!sun!cti!frazier DDD: 408-734-8533
daveh@cbmvax.cbm.UUCP (Dave Haynie) (03/05/87)
> Just the other day, I was trying to corrupt a Macintosh disk so that I could > re-format it as single-sided. So I took the disk and but it in front of > this big Hitachi monitor that I use and hit the DEGAUSS button, I held > it there for a while with the button down until the screen stopped > doing the funny things it does during degaussing, then waited for a while > and repeated this several times. The net effect on the disk was.... nil. > The Mac read the disk sans hitch. No files lost or anything. What does > this tell me? The chance of accidentally wiping out a disk by exposure > to a monitor's electro-magentic fields is virtually zero. No, actually, this tells you that the chance of random electromagnetic fields wiping out a disk is directly proportional to the importance of that disk's information. Is is a well known relationship. Since the data on the second side of that disk not only wasn't important to you, but was actually getting in your way, the chances of it being damaged at all were very close to NIL. A stronger field will be required. > -Rico -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ __ ____ ____ _____ _____ _____ Dave Haynie /// / _ | / __ \ / _ \ / _ \ / _ \ Commodore Technology /// / / | | /_/ | | | | | | | | | | | | | | |\ /// / /__| | ____/ | | | | | | | | | | | | | |\\/// / ____ | / ____/ | | | | | | | | | | | | \\// / / | | | |____ | |_| | | |_| | | |_| | {ihnp4,etc.}!cbmvax!daveh \/ /_/ |_| \______| \_____/ \_____/ \_____/ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~