Persistent floppy

[time]

A customer runs Win2k SP2 on an Athlon PC that's about 9 months old. He just called with a rather unusual problem.

When he puts a floppy disk in the drive, he can read it okay and view the directory.

But if he replaces the disk with another, Explorer continues to display the directory from the first disk.

If he refreshes Explorer, it remains unchanged. If he closes and reopens Explorer, he gets the same result.

If he removes the floppy, Windows prompts him to insert a disk, after which it redisplays the original directory. If he copies files to the floppy, the new files appear merged with the displayed directory, even though it may be a blank disk.

In short, the only way he can get it to read a second disk is to reboot the PC!

He suspects the problem started around the same time he installed some faulty software (some sort of CD database, I think, which he then uninstalled). But it's only a suspicion.

So, has anyone else come across anything similar? Any wild ideas on tracking down the culprit?

 

[NRG = mc²]

Reinstall Windows. (yeah, flame me!) [/quote]

 

[P5-133XL]

On floppy drives there is sensor that changes state when the floppy is removed. This signal indicates to the OS that its cache needs to be updated when refreshed. If the sensor blocked/broken then the OS will not be able to notice that the drive has been chanced and thus will keep looking for data solely at the cache and will not update the cache. This is the most likely senario. Your customer should replace the floppy drive (it is not worth taking apart and fixing).

It is also possible that the floppy cable has been cut or that a pin has broken because this signal has its own dedicated line. So make sure that the MB pins are intact, the cable is still intact, and that the floppy connector pins are still intact.

 

[NRG = mc²]

Wow, are floppy drives that advanced? Perhaps its the floppy drive after all...

 

[time]

That's what I thought Mark, but note that the OS does seem to be able to detect when there is no disk in the drive.

 

[Tea]

Mark, as always, is perfectly correct. There is one wire in the cable which is dedicated to sensing media change. I'm not sure how practical these tips are, but a couple of things you can play with are:

(i) Try forcing a media re-detect from the keyboard. The key combination is CONTROL-C. Old farts like Tannin remember the days when you had to press CONTROL-C every single time you changed a floppy, otherwise you would corrupt your FAT. This was one of the best things about CP/M 3.0 as compared with the old 2.2: it introduced automatic media change detection. But you can still use the same old keystrokes to force from the command line in most modern operating systems. Certainly Win 9.X, perhaps the NT family too.

(ii) Boot off floppy, or off CD, and see if the problem is still there. If it is, then it's hardware. (OK, you knew that already.)

(iii) From the command line, go to the B: drive. This certainly works in Win9X, I guess it does with the NT family things too. It should ask you to insert the disc for drive B: - another hangover from the days when computers had only one floppy drive and no hard drive.

 

[P5-133XL]

Wow, are floppy drives that advanced? Perhaps its the floppy drive after all...

No, it was because the drives are not advanced that this signal line is needed. Without it the computer would need to constantly check the drive to see if it had been changed. Accessing the floppy is very slow and very CPU intensive: There is no DMA or anything like that.

 

[Barry K. Nathan]

No, it was because the drives are not advanced that this signal line is needed. Without it the computer would need to constantly check the drive to see if it had been changed. Accessing the floppy is very slow and very CPU intensive: There is no DMA or anything like that.

Actually, floppy controllers do use DMA, and it's not noticeably CPU intensive under Linux or *BSD...

 

[Barry K. Nathan]

Actually, floppy controllers do use DMA, and it's not noticeably CPU intensive under Linux or *BSD...

PC floppy controllers
I forgot the word PC in my previous post (the old 68K Macs use PIO on their floppy controllers, which is why the mouse pointer can't keep up during floppy accesses on those machines).

 

[i]

I think I'm too tired to explain what I mean, but here goes anyway . I don't have a Windows 2000 system to look at, but does it continue the tradition of allowing a drive to be set as a REMOVEABLE device or not?

Under Win9x, all you have to do is look at the hardware in the System part of Control Panel and you can view the details for any drive (DMA settings, drive letters, etc.). One of the options is "Removable device". Maybe the floppy drive has had that option UNselected.

Urgh. Good night.