Card swapping, CHKDSK, and file damage

Unlike the HP 200LX user manual admonishments never to insert or remove a card while the power is on, real life usage means that power on card swaps are going to happen. One prime example... you CANT power down when hooked to the AC adapter with NiCds.

From my three years of experience with the LX, swapping cards with the power ON should not create any physical problems for memory or other cards, if you deal with the open program issues first. Even if you take the precaution of powering down before swapping, there are still some critical remaining dangers for file damage from swapping cards, if you have applications open at the time of the swap.

Use some common sense to prevent damage to any files that may be open when you are ready to remove a card. ALWAYS press the & key (which will take you to the More Applications screen) and see if any applications are running. (If you've chosen the icon display of applications, those applications that are open will be highlighted. If you use the list of applications, the status column will say open for those apps that are running.) If applications are open, enter each running application and Quit each one before removing any card, or choose MENU, Application, Close All from more Applications.

To restate, it is vital to NEVER remove a card while ANY program other than FILER is running. You may get away with it by swapping a memory and modem card and then re-inserting the same memory card, but you will NOT get away with it if you swap one memory card for another.

As an additional precaution, when I insert a different memory card, I also go to the DOS prompt for the card drive and press (Ctrl)+(C) to force DOS to re-evaluate the contents of the default drive. While DOS is pretty good about noticing removable drive changes, you cannot always rely on this happening, and the penalty for writing to the wrong disk is simply too high.

The CHKDSK DOS command deals with DOS errors and not program file errors. CHKDSK errors happen when a program has a file open and has written data to the disk, but has not yet updated the file directory information (the FAT). When a disk is removed (or a reboot occurs) in that state, the file data that is not associated with a directory entry becomes a lost cluster.

CHKDSK will also spot file cross links where two directory entries indicate that they each have sections of files stored at the same disk location. This type of damage is typical of disk swap problems; but, again, the recovery result is not going to be pretty... especially on files that are tightly packed to preserve disk space, such as the address or database files.

OFF doesn't really mean off with the HP 100/200LX. Damage happens even if the LX is powered down, because the computer is not really turned off like your desktop when you power it down. (You might want to read that last sentence again. Its very important.) DOS is actually running in a low power state when the screen is blank... so if you have your data files open when powered down, and you switch cards, you create the conditions where files are going to be corrupted.

While it also seems that most of the LX applications are reasonably good about housekeeping in writing things to disk immediately after you save them, even so, swapping memory cards sets up almost any application to write data onto a different disk at a hardware location where it should be writing it on the old disk, and that location could contain another vital file.

That also means that CHKDSK cannot give you accurate information about the condition of your files. The best way to determine file damage is to look at the file by editing it, or running a report, or something, to the screen that will allow a fast view of all of the file contents.

Finally, the CHKDSK /F option will result in a prompt to save lost clusters to files if the process finds some. Always answer Yes to this question, and when CHKDSK ends, you will find new files in the root directory with number names and the extension .CHK.

For example, if you were in the middle of an edit of the only copy of your great American novel and you lost it, there is a possibility that you MIGHT find the lost portions in these CHK files. The file remains will not be pretty, but many times you can either cut and paste sections back together, or (in the case of a lost PhoneBook file) do a search to find an address or phone number that may be otherwise lost forever.

After you view the contents of the .CHK files and determine that they don't contain info you need, you can safely delete them.

Beverly Howard , 75533.1712@compuserve.com http://ourworld.compuserve.com/homepages/bevhoward/