🚀 go-pugleaf

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