jlb@aipna.ed.ac.uk (John Beaven) (03/05/90)
Hi folks I wonder if there's anybody out there who can help me with what looks like a floppy drive controller problem. I have recently bought a second hand 720k 3.5" drive to be used as a second drive (B:) on my AT clone (a Tandon Target running MS-DOS 3.3 - drive A: is the usual 5.25", 1.2M). It seems to be working fine in that it reads and writes ok, but it looks as the directory contents are being buffered in a funny way. If I start up the machine and do DIR B:, I get the contents of drive B: as expected. If I then change the floppy in drive b:, and do DIR B: again, I still get the contents of the first floppy, even though the light on the drive goes on and it looks as if the machine is reading it. In fact I don't think it is: if I leave drive b: empty and do DIR B:, the light goes on, and I still get the contents of the previous floppy. The only way to find out the contents of drive b: is to do DIR A:, and then DIR B:. That seems to make it forget the previous contents of b:. I vaguely remember that CP/M had a bug -sorry, feature- like that, in that you had to tell it that you had changed floppy in the drive, or it wouldn't notice. But it's the first time I've seen this on a clone 8-{ Can anyone give any advice? Is this a problem with the drive or the controller? (the controller is on the motherboard, btw). Thanks for any help. John jlb@aipna.ed.ac.uk
sorc@carina.unm.edu (Paul Caskey) (03/06/90)
jlb@aipna.ed.ac.uk (John Beaven) said: John> If I start up the machine and do DIR B:, I get the contents of John> drive B: as expected. If I then change the floppy in drive b:, John> and do DIR B: again, I still get the contents of the first John> floppy, even though the light on the drive goes on and it looks John> as if the machine is reading it. ... This is a long shot, but do you have either of the floppies in question write-protected? I've had similar bizarre happenings like that on an AT and that was why. Don't understand why, so don't have an answer... -- /*********/ Paul Caskey pcaskey@ariel.unm.edu Only lawyers represent anyone's ideas but their own. /*********/
JIW2@psuvm.psu.edu (John Wagner) (03/07/90)
Hi folks >I wonder if there's anybody out there who can help me with what looks ke >like a floppy drive controller problem. >I have recently bought a second hand 720k 3.5" drive to be used as a seond >drive (B:) on my AT clone (a Tandon Target running MS-DOS 3.3 - drive A >is the usual 5.25", 1.2M). It seems to be working fine in that it readsand >writes ok, but it looks as the directory contents are being buffered ina >funny way. >If I start up the machine and do DIR B:, I get the contents of drive B:as >expected. If I then change the floppy in drive b:, and do DIR B: again, >I still get the contents of the first floppy, even though the light on he drive >goes on and it looks as if the machine is reading it. In fact I don't >think it is: if I leave drive b: empty and do DIR B:, the light goes on and >I still get the contents of the previous floppy. The only way to find ot the >contents of drive b: is to do DIR A:, and then DIR B:. That seems to mae it >forget the previous contents of b:. >I vaguely remember that CP/M had a bug -sorry, feature- like that, in tat you >had to tell it that you had changed floppy in the drive, or it wouldn't >notice. But it's the first time I've seen this on a clone 8-{ >Can anyone give any advice? Is this a problem with the drive or the conroller? >(the controller is on the motherboard, btw). jlb@aipna.ed.ac.uk John: After installing a CompuAdd 1.44M floppy drive and controller in my old XT Portable, I had exactly the same problem. I posted this to my local computer club BBS, and the reply I got from a local PC repairman was to disable lead 34 between the drive and the controller card, either by a jumper if there is one, or by putting a piece of tape over the #34 contact on the drive. I was told this is a very common problem. I can't vouch for this fix, since I decided to wait until the next time I open up the PC to try it out. If you try it, please post the results to this newsgroup. In the meantime, I have found that doing a CTRL/C after changing disks forces a read of the disk's FAT, and DOS then knows you have a new disk in the drive. Pretty heavy-handed, but it works as a stopgap measure. John Wagner
marshall@wind55.seri.gov (Marshall L. Buhl) (03/07/90)
sorc@carina.unm.edu (Paul Caskey) writes: >jlb@aipna.ed.ac.uk (John Beaven) said: >John> If I start up the machine and do DIR B:, I get the contents of >John> drive B: as expected. If I then change the floppy in drive b:, >John> and do DIR B: again, I still get the contents of the first >John> floppy, even though the light on the drive goes on and it looks >John> as if the machine is reading it. ... >This is a long shot, but do you have either of the floppies in >question write-protected? I've had similar bizarre happenings like >that on an AT and that was why. Don't understand why, so don't have >an answer... I once released a floppy while it was being used. I got the standard (A)bort, (R)etry, (F)ail message, swapped floppies and told it to retry. The PC finished writing to the new disk and wrote the updated directory of the original disk onto the second disk. This is probably a long shot too, but maybe... -- Marshall L. Buhl, Jr. EMAIL: marshall@wind55.seri.gov Senior Computer Engineer VOICE: (303)231-1014 Wind Research Branch 1617 Cole Blvd., Golden, CO 80401-3393 Solar Energy Research Institute Solar - safe energy for a healthy future
alun@neabbs.UUCP (ALUN SAUNDERS) (03/08/90)
Hi there, I have been having vaguely similar problems recently wxcept with 5,25" drives, and can maybe help you out. It appears that pin 34 is used differently on AT and XT classs machines, and for this reason many drive manufacturers allow you to change the use by means of a jumper. To be more precise, this line can be used as either a READY signal or a disk change signal. Pin 34 needs to be configured as a disk change signal for use on AT's. This lets DOS know that a disk change has occurred and that it should make no assumptions about the contents of the disk, i.e. it should re-read the FAT, directories etc. I have seen people reccommending snipping the cable or sticking sticky tape over the edge connector, but since the signals are active low I suspect that this would have the effect of making DOS think that the disk had been changed after every disk access which sounds like overkill to me. I would recommend that you hunt for a jumper on the drive that looks a likely candidate. On my Chinon drive there are two jumpers marked RDY and DKC for example, on a TEAC drive the same jumper is marked DCRY (three pins, jumper on left hand 2 = disk change, right hand 2 = ready). I know this is a bit vage, but happy hunting ! Alun Saunders
vera@cadence.com (Vera Vallentin-Price) (03/08/90)
>>jlb@aipna.ed.ac.uk (John Beaven) said: > >>John> If I start up the machine and do DIR B:, I get the contents of >>John> drive B: as expected. If I then change the floppy in drive b:, >>John> and do DIR B: again, I still get the contents of the first >>John> floppy, even though the light on the drive goes on and it looks >>John> as if the machine is reading it. ... > When I've experienced the problem you described, the cure for me was to move a jumper on the floppy drive from the "A" to the "B" position. Look for it on top of the drive, toward the end (away from the drive opening). You'll find a three pin 90 degree angled connector that may or may not be labeled with the letters A and B. If its not labeled, just move the jumper in the second possible position (always covering two of the three pins). That should take care of your DIR B: problem. Vera.
scheer@cell.mot.COM (Jon Scheer) (03/09/90)
The problem is that your floppy thinks it is connected to an XT, and it is using pin 34 as a Drive Ready indication. When you hook up a 3.5" floppy to an AT, you want pin 34 to indicate Disk Change. Look on the logic board on the floppy. There will probably be a jumper labeled DS/RDY or some such thing. Usually it is three pins where you jumper the middle and one of the outside pins. This one had me going for months... (I have a lot of 'war stories' about hooking up 3.5" drives.) Like someone else stated, there is another way you can get around this problem -- sort of. You need to hit ^C at the Dos prompt after changing disks. One 3.5" floppy drive that I have doesn't have any jumpers on it. I get the impression that it was designed for use with an XT. But I wonder if I can get it to work on an AT if I put a capacitor in series with pin 34 so the AT would only see pulses... Hmmm... Something to try this weekend... (Any bets?? :-) Hope this helps. Jon 3/8/90 ...{uunet | mcdchg}!amtfocus!outback!wombat <-- Home ...{uunet | mcdchg | gatech | att}!motcid!scheer <-- Work amtfocus!outback!wombat@UUNET.UU.NET or F1JON@ISUMVS.BITNET <-- Bitnet amtfocus!outback!wombat@chg.mcd.mot.com <-- Internet "In search of the Warmer Blid Custard Mite Of Glut..." -- DM