Hard drive only partially accessible

[Bill-kun]

Dell model System 200, a big horizontal beige metal box, 286.

I am trying to get an old hard drive working to use it as a drive D. It is a Seagate ST-225, 21 MB. According to redhill.net.au, this is a type 2 hard drive. I have checked that the jumpers on the hard drive are correct. The hard drive is plugged into both the controller ribbon cable and the data ribbon cable.

I have to boot from an old DOS 6.20 boot floppy. The modern DOS 6.22 floppy I made will not work in this computer for some reason. The boot up process always says "Hard disk failure." I can continue the boot process and from the DOS prompt, I can switch to C:. I can do a dir command in some directories but not in others. I can read certain files but not others. The two errors I keep getting are "Sector not found reading drive C" and "Data error reading drive C."

I had enough room on the old DOS 6.20 boot floppy to copy IDESDI.EXE onto it. Using IDESDI.EXE results in "An AT controller was found. Memory allocation error. Cannot load COMMAND, system halted."

Using ScanDisk on my DOS 6.20 boot disk results in "ScanDisk encountered a data error while reading the FAT on drive C. This error prevents ScanDisk from fixing the drive."

I know that the FAT is the file allocation table, where the filenames and their locations are indexed on the disk. I am hoping that the FAT is not corrupt and I am just doing something not quite right.

[bakemono]

It sounds like some parts of the hard disk are not readable. That could be because the disk or controller is failing or because the controller is not the same one that was originally used to write the data.

Since you said you wanted to use it as 'D' I am wondering if that is a disk which you have taken from another machine with a different ST-506 controller. Do you still have the controller that it was connected to originally? Because that would be the best bet to recover the existing files on the disk, if you need them.

[SomeGuy]

First of all, I'd be suspicious of the system's health. Before tackling the hard drive, verify the rest of the machine is working with some diagnostics. Test RAM, CPU, floppy, video, etc. Also verify that the BIOS "type 2" on this machine actually matches an ST225. Some machines COULD have customized BIOSes with alternate parameters.

What hard drive controller card is in the machine?

Do you need any data off of that drive? If it has such problems, I'd try to copy anything off before making changes.

If not, I'd strongly suggest just re-low level formatting the drive, FDISK, and then DOS format. Although if sectors in the FAT are damaged, you may wind up with FDISK or FORMAT barfing.

If it succeeds at formatting, I'd then follow up with spinrite.

[Bill-kun]

It sounds like some parts of the hard disk are not readable. That could be because the disk or controller is failing or because the controller is not the same one that was originally used to write the data.

Since you said you wanted to use it as 'D' I am wondering if that is a disk which you have taken from another machine with a different ST-506 controller. Do you still have the controller that it was connected to originally? Because that would be the best bet to recover the existing files on the disk, if you need them.

It's highly unlikely that the controller card is failing since it and the cables and everything else about this computer have been working perfectly on its ST-251 HDD since I unearthed this computer about three months ago. The controller card is a WD1003-WA2, copyright WDC 1985.

I currently have only one 20-pin data cable, so the computer is limited to only 1 hard drive in a given boot session.

I verified with AT_FDPT that type 2 for this BIOS matches the CHS for ST-225 (615, 4, 17).

I am 95% certain that the ST-225 was not written with this same controller card, but was from another vintage computer we had in December 1994, going by the most recent file dates. We no longer have that computer and I have no idea of its model or what controller card it would have had.

I don't think we absolutely need any of the data on this drive, but I sure want to get it all properly if I can. Someone in our family mentioned the ST-506 standard as well, so I will read what I can about that.

Any other advice?