KENNEDAM%WWPS@dupont.com (Tony Kennedy) (08/11/89)
HI all, Is there a drive head alignment program floating about the net? My df0: is giving me read/write errors on a few disks. Those disks read just fine on my brand new df1: drive. Could the alignment be the problem or maybe dirty heads? Help! ...Tony >-----------------------------------------------------////---------------< | Tony Kennedy | Any resemblance | //// AMIGA | | Project Engineer | between these and my |\\\ //// The computer | | Setpoint Inc | employers opinions is | \\\/// For the best | | | pure coincidence. | \\\/ of us. | >------------------------------------------------------------------------< | INTERNET : kennedam%wwps%dupont.com@relay.cs.net | >------------------------------------------------------------------------< | "Don't tie your sister up with dental floss." My girlfriend to the | | children she's babysitting | >------------------------------------------------------------------------<
armhold@topaz.rutgers.edu (George Armhold) (08/19/89)
Hi, I'm working in an environment where I'm shuffeling between an A1000 at home and an A2000 at work. It seems that one of these machines (or possibly both) has an alignment problem with one of their floppy drives. Sometimes when I try to boot from a Workbench disk the machine just grinds away at the disk. It takes about 5 minutes to boot from a disk that usually boots in 3. If I try booting a few times the problem sometimes goes away. I used to fix this problem in the past by simply replacing the bad disk, but this is starting to happen on 1 week-old disks now. Are there any programs in the public domain that will test the alignment of a disk drive? Thanks, -George
cmcmanis%pepper@Sun.COM (Chuck McManis) (08/22/89)
(George Armhold) writes: > ... Sometimes when I try to boot from a Workbench disk the >machine just grinds away at the disk. It takes about 5 minutes to boot >from a disk that usually boots in 3. If I try booting a few times the >problem sometimes goes away. ... What your problem is, is called disk validation. When you write to an Amiga floppy the "bitmap" which shows which blocks are free on the floppy gets updated but not initially written. (This is an optimizing solution to prevent having to write all the time to the disk) Anyway, after a your last write to the disk *WAIT 3 SECONDS*, the disk will suddenly write again! That is the handler flushing the bitmap back to the disk. If you don't wait and pop out the disk, there won't be anything wrong with it, rather it will just not be validated. The next time you pop it into a drive to boot or just read it, the handler will note that it isn't validated an then proceed to read *EVERY* directory and file header to make sure the bit map is correct. This can take a noticebly long time especially if you have lots of files on the disk. Once it's been validated thought you won't have to validate it again (until it has been written to) and so reboots from that point on will happen much more quickly. --Chuck McManis uucp: {anywhere}!sun!cmcmanis BIX: cmcmanis ARPAnet: cmcmanis@sun.com These opinions are my own and no one elses, but you knew that didn't you. "A most excellent barbarian ... Genghis Kahn!"
hull@hao.ucar.edu (Howard Hull) (08/22/89)
In article <122819@sun.Eng.Sun.COM> cmcmanis@sun.UUCP (Chuck McManis) writes: >(George Armhold) writes: >> ... Sometimes when I try to boot from a Workbench disk the >>machine just grinds away at the disk. It takes about 5 minutes to boot >>from a disk that usually boots in 3. If I try booting a few times the >>problem sometimes goes away. ... > >What your problem is, is called disk validation... >... >isn't validated an then proceed to read *EVERY* directory and file header >to make sure the bit map is correct. This can take a noticebly long time >especially if you have lots of files on the disk... > GAWRSH, Chuck, you usually get _everything_ when you report the cause of a problem. It's a surprise to see you screw up like this! :-) You should've noted that there's a problem with situations where the Workbench is sooooo full that there's not even a single block left in which to write the new bitmap (keeping in mind that AmigaDOS insists on writing the new bitmap before it "unlinks" the old one). Under such circumstances, AmigaDOS will not write the bitmap until it can find a free block - but since the file writes go ok, it doesn't report any kind of error (that's just as well, since there isn't any error, just a pending operation it can't finish). Thus if you remove your completely full Workbench, it comes out with the bitmap valid flag set to zero (on a 880K floppy that's Root Block (880) longword 78 in the ever so famous track 40). A validated floppy has -1 in this longword. So if you filled your Workbench to where the Info command shows 0 blocks remaining, issue a "DiskChange DF0:" command (assuming DF0's the device where you had the workbench placed) before you pull out the disk - or pull it out and put it back again before you try to reboot with it). DiskChange will cause AmigaDOS to check the root block in order to identify the disk, and will result in a call to the l:Disk-Validator handler when the BMFLAG is found to be cleared. One other thing...if you ever get a disk that causes a crash when you try to Read, Copy or Delete a file or directory you can usually recover (first make a copy of the disk with DiskCopy - but be warned that the copy will crash in the exact same delightful way...). Use a disk editor (i.e., Sectorama, DiskZap, or DiskEd) on the copy to fetch block 880; clear longword 78, correct the checksum, and write the rootblock back to the copy. When the editor releases the disk back to AmigaDos, the validator will be summoned before very much is done with the disk's filesystem, and the problem causing the crash will likely be cleared up before the file system can get involved with it. This procedure will work on disks that are so hosed that they cause a crash upon insertion - if one merly opens the disk editor on a formatted blank disk, and then (after the editor has locked the disk away from AmigaDOS' access) substitute the hosed disk before pulling the root block into the editor's buffer and clearing the BMVALID flag. Have fun... > >--Chuck McManis >uucp: {anywhere}!sun!cmcmanis BIX: cmcmanis ARPAnet: cmcmanis@sun.com >These opinions are my own and no one elses, but you knew that didn't you. >"A most excellent barbarian ... Genghis Kahn!" Howard Hull - more barbaric than Genghis Kahn, but not nearly as excellent... hull@hao.ucar.edu
ecarroll@csvax1.cs.tcd.ie (Eddy Carroll) (08/23/89)
(George Armhold) writes: > ... Sometimes when I try to boot from a Workbench disk the > machine just grinds away at the disk. It takes about 5 minutes to boot > from a disk that usually boots in 3. If I try booting a few times the > problem sometimes goes away. ... In article <122819@sun.Eng.Sun.COM>, (Chuck McManis) replies: > What your problem is, is called disk validation. [ Good explanation of disk validation deleted ] > This can take a noticebly long time especially if you have lots of files > on the disk. Once it's been validated thought you won't have to validate > it again (until it has been written to) and so reboots from that point on > will happen much more quickly. The disk validator itself isn't too slow; the real problem is that it's trying to validate the disk at the same time as the startup-sequence is executing. This results in two seperate processes trying to access the disk at the same time, and sends AmigaDOS scurrying back and forth over the disk surface reading blocks alternately for each process. This makes things MUCH slower than you might otherwise expect, and is accompanied by what sounds like AmigaDOS trying to eat your disk (it doesn't actually do any damage, other than adding a little extra wear and tear to the drive mechanism). When this happens, the best idea is to stop the startup-sequence from executing, and let the disk validator get on with its work. You can do this by pressing CTRL-D, and then rebooting after the drive has stopped for more than 4 seconds or so. An alternative is to just press SPACE, which will pause the startup-sequence, the next time it tries to output a message. When all disk activity has stopped, just press BACKSPACE to resume the startup-sequence. -- Eddy Carroll ----* Genuine MUD Wizard | "You haven't lived until INTER: ecarroll@cs.tcd.ie | you've died in MUD!" UUCP: {..uunet}!mcvax!ukc!cs.tcd.ie!csvax1!ecarroll | -- Richard Bartle
douglee@becker.UUCP (Doug Lee) (08/24/89)
In article <Aug.19.12.26.52.1989.18198@topaz.rutgers.edu> armhold@topaz.rutgers.edu (George Armhold) writes: > >Hi, > I'm working in an environment where I'm shuffeling between an >A1000 at home and an A2000 at work. It seems that one of these >machines (or possibly both) has an alignment problem with one of their >floppy drives. I suggest that you disassemble your drive and give it a thorough cleaning with PURE isopropyl alcohol, especially the heads, but be sure and clean out any hair or fuzz that may be migrating to the head area. Also make sure that nothing is blocking the optical sensors for track 0, write protect and disk inserted. Some drives have little mechanical switches for disk inserted and write protect. Make sure they move freely and aren't bent. If they are bent and binding, bend them back VERY carefully. >Are there any programs in the public domain that >will test the alignment of a disk drive? To do this, You need and oscilloscope and a special alignment disk made on a calibrated drive. You can get these from drive manufacturers and people who make drive testing equipment. I got mine from a company called Lynx in Markham Ont Can, who make drive exercisers. It cost $100.00 Can. Once you have one of these, you have to move the head to the track indicated on the disk where a ' cat-eye ' pattern is found. What this amounts to is a couple of analog signals recorded just before and just after the track you're on. Their amplitudes change sinusoidally, and are out of phase, so the result is that you see two humps on the oscilloscope, which should be of equal amplitude. If they are not, you have to loosen the screws holding the head stepper motor and rotate it. This is VERY touchy and you could easily lose the track you're on completely. If this happens, just step the drive in and out until you find the signal, and then you know where you are and which way to adjust. Unless you feel comfortable with mechanical stuff requiring extremely delicate tweeking, you may not feel like doing this. The other part is adjusting the index pulse from the drive so it matches areference pulse recorded on the disk. In other words, you want the index pulse out of the drive to happen at the proper time relative to the pulse recorded on the disk. I forget if it's at the same time or there is an offset, without hauling out a drive manual. The oscilloscope must be a dual-trace model and is connected to test points in the drive, with the scope channels added together and inverted with respect to each other. The test points are on the front of the NEC drives, beside the light connector. (The two outside ones). On one variation of Matsushita drive, the test points are on the bottom labelled T1 and T2. You will have toi solder little wires to them to hold the scope probes on. Various models of drive will be different. As far as software, I have just hacked on the example trackdisk device code in the RKM to make it do what I want, for the occasion at hand. You could have a look at this. I have thought of making a program just for stepping drives for servicing, but never gotten around to it. If there's any interest, I may. Does anyone on the net reading this know where to get manuals and parts for all these various floppy drives? If so, mail or a posting would be appreciated. > >Thanks, >-George -- Doug Lee douglee@becker 416-461-5357
new@udel.EDU (Darren New) (08/25/89)
Another method, if you notice the GRONKs right away, is to reboot. Before the DOS has openned the window, start typing over and over (e.g., jkljkljkljkljkljkljkl). Dow will start the console in the initial window and then try to put out the copyright, which will block because of typeahead. Let the disk finish, and the ^X. -- Darren