Microsoft KB Archive/60035

Directory of Floppy Disk Not Updated PSS ID Number: Q60035 Article last modified on 01-22-1993 PSS database name: O_MSDOS

3.2x 3.3x 4.00 4.01

MS-DOS

Question:

I am using an AT style machine and when I put a floppy disk in the disk drive and do a DIR on it, DIR responds with the proper directory listing; however, if I then try to do a DIR on another disk in the same drive, I get the directory listing from the first disk. Why does this happen?

Response:

AT style machines and 386 based machines use what is known as a “disk change line.”

When you open the drive door, the door sends a signal to the drive, which then sends a signal to the controller, which in turn sends a signal to the BIOS. This signal tells the computer that the drive door has been opened and the drive buffer can now be flushed. If this signal is not sent properly, the above error will occur (you will continue to get the same DIR listing). This error generally indicates a problem with either the disk drive, the controller, or the BIOS.

To ensure this is a problem with the hardware, you should first check the documentation from your computer manufacturer. If this is not useful, you may wish to contact your original hardware dealer or another local hardware dealer.

Note: Most PC and XT style machines do not use the disk change line.

Additional reference words: 3.2x 3.3x 4.00 4.01 noupd

Copyright Microsoft Corporation 1993.