TITLE: How to Avoid Invalid Disk Change Errors During Installation PRODUCT: Ami Pro 2.0 DATE: 11-Oct-1991 PROBLEM: The error "Invalid Disk Change" appears when program disk 2 is inserted into the specified drive. This error continually appears and the installation cannot complete. SOLUTION: The Invalid Disk Change message is usually generated by the DOS Share program. This program is normally used by DOS 4.X to recognize a drive partition larger than 32MB in size. Another aspect of Share is that it monitors read and write operations. If a read or write operation takes place when a disk has been changed in the middle of the operation, Share looks at the volume label to determine if it is the same disk that was previously in the drive. If it is not, DOS sends an invalid disk change error message and requests that the proper disk (identified by the volume label) be reinserted into the drive. This functionality exists to prevent inadvertently overwriting data. During installation of Ami Pro, Share has detected that a file is open and the same disk is not in the drive when program disk 2 is inserted, so a message appears requesting that the previous disk (program disk 1) be reinserted into the drive. There is a way to eliminate the invalid disk change error produced by Share. Add the switch /NC at the end of the command to load Share. For example, if Share is being loaded in CONFIG.SYS, the line might look like: INSTALL=C:\SHARE.EXE /NC The /NC switch disables the functionality of Share that will produce the invalid disk change error when disks are switched while files remain open. After adding /NC to the Share command in CONFIG.SYS, it will be necessary to reboot the computer to load Share again. IMPORTANT: Since the ability to monitor floppy disk changes provides security against accidentally overwriting data on a floppy disk, the /NC switch should be removed from the Share command after the Ami Pro installation is completed. If a version of Share is being used for which the /NC switch is not available, try remarking out the line that loads Share in the AUTOEXEC.BAT or CONFIG.SYS file by typing REM at the beginning of the line. Save the change and reboot the computer, then install Ami Pro. After installing Ami Pro, remove the REM from the line that loads Share. Save the change and reboot the computer. NOTE: The /NC switch for Share is not documented in the DOS manual. The information about /NC was obtained from various sources on CompuServe. A related problem that may occur during installation of Ami Pro is continually getting a prompt to insert program disk 2 even when the correct disk is in the drive. This is usually caused by a hardware configuration that does not read the drive every time a disk is accessed. Even though program disk 2 has been inserted, the computer does not read the drive after disk 2 has been inserted. When this occurs it may be possible to use the DOS DRIVPARM command to force a disk change read. DRIVPARM is available in MS-DOS 3.2 and higher but not in any version of PC-DOS. It modifies the parameters of existing physical drives attached to the system. A DRIVPARM line in the CONFIG.SYS file might read: DRIVPARM=/D:0 /F:1 There should NOT be a /C switch. The absence of /C will force DOS to read the drive each time a disk is accessed rather than search the internal disk buffers. If a DRIVPARM line already exists in the CONFIG.SYS file for the disk drive which is being used to install Ami Pro and the /C switch is present, remove the /C. The /D:0 parameter designates that the A drive is the one to be changed (use /D:1 for the B drive), and /F:1 identifies it as a 1.2MB drive. Different drive types will require different switches. Refer to a DOS manual for the version of DOS being used for complete information about DRIVPARM. Since DRIVPARM alters the characteristics of floppy drives, if it did not already exist in the CONFIG.SYS file prior to installing Ami Pro, it should be removed after Ami Pro is successfully installed. If the /C switch was removed from an existing DRIVPARM command in CONFIG.SYS, add the /C switch back to the command after Ami Pro is successfully installed.