MS-DOS Mystery!

So last summer i acquired a (rare?) Luggable 286 portable computer. It has some nice hardware, A floppy/hard disk controller, A 21Mb fuji electric hard disk, 1Mb of ram, 287 coprocessor, LCD-Panel etc. It was built around 1986-1988.

It has dos 3.21 on it, my first issue was hidden files. The command.com and some other important files were marked invisible so some software was incompatible. The normal DOS Attrib editor didn't work so i downloaded another, alternative one and figured that out.

So just yesterday i wanted to put some of my old dos game on this. I created a games directory, Within it i created a directory named "FLTSM" with the intention of extracting MS flight simulator 4 in it. However, before i could do so, Magic happened. I go in the FLTSM directory, And, to my surprise, it claims to contain the entire root directory! Every time i do dir in this folder, It shows the root directory, Including the games directory that it is contained in. I know for a fact that the almost full 21Mb hard drive can't hold the entire root directory on it twice, so i did some testing. I created a test directory labelled "TEST" in C:\
After doing that, I went back into the FLTSIM directory and sure enough, There it was, C:\GAMES\FLTSM\TEST
What's also interesting is that i can do a loop, C:\GAMES\FLTSM\GAMES\FLTSM\GAMES\FLTSM.....
Obviously something has went weird here so i did CHKDSK. it says first of all, "Errors found, F parameter not specified. Corrections will not be written to disk.", What does this mean?
Secondly, "C:\GAMES\FLTSM Invalid sub-directory entry."

I'm totally out on this one. Ideas?

Ok so i literally just figured this out. Doing chkdsk /f actually fixes the errors, After doing so, it fixes everything and creates some .CHK files in the root.
But it still bugs me, what could have caused this?!

Looks like you have problems with the filesystem (or perhaps disk and related hardware), and so the FLTSM directory points back to the root directory.

Back up everything, run CHKDSK again with /F parameter (so it will fix problems). Even better use scandisk from MS-DOS 6.2+ or the Norton Disk Doctor. For scandisk you don't need to install newer MS-DOS, just make a system diskette and copy scandisk.exe to it.

Sounds like the disk's directory structure and file system is hosed. Something like Norton Disk Doctor would probably be able to straighten it out. So would a DOS format.

Its known as 'cross linked' entries, directories in this case. Just means that the linked-list of clusters that is the FAT is not entirely correct. At this age, it would be a good bet to run a low-level format on the hard drive anyway (after which you'll need a DOS boot disk to run FDISK to create a new, bootable partition and then FORMAT c: /S to install the basics of DOS).

Ok. I think the best solution will be to do a low-level format. But before i do that, I want to back up everything. About 18Mb of data, Onto 720K floppies. I have tons of floppies anyways and i will be re-using them after restore. I was thinking of using FastBack Plus for this. I will be using SpeedStor to run the low level format since my controller doesn't have it's own bios.

I you use SpinRite you don't need to back it up. SpinRite does a non-destructive LLF.

I'll differ with the others here.

I wouldn't bother with a LLF unless a surface scan showed problems. A normal FORMAT should be good enough--and perhaps that's going too far.

CHK files are not necessarily the result of cross-linking, they can be "orphan" cluster chains. If you had a system crash or power failure (or even a RAM error), that can create cross-linked or "orphan" clusters, particularly if you have any sort of disk caching installed.

Bottom line I think is that if a surface scan comes up clean and CHKDSK shows no more errors, just solider on.

I think the drive has some bad sectors i need to mark out also. I'll just do a low-level format anyways, For the first time in roughly 22 years on this drive.

Running backups onto floppies now. Mmm! I love that clicking they make!

Also, I highly recommend FastBack, Amazing program!

Mac said:

Running backups onto floppies now. Mmm! I love that clicking they make!

Also, I highly recommend FastBack, Amazing program!

Click to expand...

Be careful, old floppies doesn't tend to be reliable, usually floppies are bad stored, and this results in bad media.

lucasdaytona said:

Be careful, old floppies doesn't tend to be reliable, usually floppies are bad stored, and this results in bad media.

Click to expand...

I'll second that!

If you have (or can buy/make) a null-modem cable and have a DOS-capable second computer I'd do a second backup over the serial port (if anything on that disk is in fact important).

A parallel port Zip drive, SCSI adapter (with SCSI drive or tape attached) or even a DDS tape drive would be what I'd use--or simply attach a second MFM drive and copy stuff over to it.

How about an IDE drive? Can't you plug one of those in next to an MFM?

Depends on the original--AT IDE and AT MFM share the same I/O ports. The XTIDE would probably work, however.

MikeS said:

I'll second that!

Click to expand...

I'll third that!

In fact they are so unreliable that at those days I was disk-copying each and every disk whenever I wanted to move something to some other guys PC. Whenever the disk showed a "data error reading" we were inserting the clone.
The best backup option is an IDE-USB2.0 adapter. You can copy the data to your modern PC in full-speed and use whatever error-scanning software you want, that will also determine if the problem is the HDD itself and not some sort of I/O controller issue, or RAM/mainboard instability due to age.

Oh, and BTW, if the HDD has a problem, it will more likely have bad clusters, visible in a scandisk or Hd-Tune sufrace scan. File system errors without bad clusters are often caused by other reasons, like powering-off while the HDD has not finished the job or system instability.

When it comes to the LLF, I've never done it to a HDD. I remember the seller of my first PC (386) telling me "don't even think about that" and in case I would do so, he would "void" my warranty.

It's curious. I routinely do 8" and 5.25" data retrieval. Amazingly, errors are very few, unless they were the result of some operator error. I find 3.5" floppies to be much less reliable. I recently did a job with over 300 Kaypro floppies--not a single unrecoverable error, even though some were DSHD media written with DSDD information.

On the other hand, 3.5" floppies are quite unreliable unless they're 720K DD. If the drive is aligned and clean, there's no reason why perfectly reliable 360K disks can't be written on good media and last the next 20 years.

I trust floppies more than I trust QIC or DDS tape.

Yea, it is funny IBM decided that smaller 3.5 inch high density disks should hold more data than the older 5.25 inch high density disks. Good thing 2.88MB floppies didn't catch on!

I do agree that I find that 3.5" floppies are less reliable. I have bought lots of random 5.25 floppies and most actually were usable. Even when I bought a bag from goodwill that were just strewn about.
I have boxes of new 3.5 and have had more dead ones in there than the used 5.25's.

With the 3.5"s, I wonder how much is the original specs and how much is a deteriorating quality of manufacture as prices came down.

I have some 20year-old Microsoft distribution disks for Dos/Win3.11 that seem to be bit-perfect and I still use the originals.

Also find some NOS no-name disks fail on first attempt to format. I'd be guessing there was skimping on the coatings - composition or quantity. Chuck might know?

Rick