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Low Level Formatting Model 25 Hard Drive

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evildragon

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How do I low level format the HD in the model 25? It seems to have a bad low level format, which has been causing a big head ache for me, as high level formatting never fixes it.

But the normal debug command just hard locks up the computer.. Is there even a built in thing for this to low level format?
 
On most versions of the IBM diagnostic/reference disk, theres a hidden option to low level format the drive and some other utilities.

To get to these options, press CTRL+A at the main menu (after the blue IBM welcome screen) to access the utilities. Then select something like Low Level Format.

If that doesn't work, try SpeedStor.
SpeedStor is at,

http://www.minuszerodegrees.net/software/speedstor.htm
 
Actually, I found it, it's on the advanced diagnostic disk, and you have to start the system checkout before it even shows up. It found 29 bad sectors!
It's low level formatting now. Too bad I couldn't recover my data though.
 
Wowee!!

Code: 
FIXED DISK DRIVE C
    CONTAINS
FLAGGED DEFECTIVE TRACKS  -     92
TRACKS UNABLE TO BE READ  -      6
GOOD TRACKS               -   2350
PRESS "ENTER" TO CONTINUE
?

That's a lot of defective tracks..

Though, after a low level format, 0 are defective, and only 2 are unable to be read. Is that normal?

EDIT: Doing a high level format, it still keeps stopping during the format to make those constant re-seeking sounds.. Argh!!
EDIT: After a high level format, it says 20480 bytes in bad sectors.

So, in which order am I supposed to do this, unconditional first, or conditional first? Maybe I did this in the wrong order.
 
Last edited:
Glad it worked for you! I guess it means that none of them have NEVER had any previous problems and two sectors are being very stubborn to read. What OS are you going to install?
 
Not too sur. I would install DOS 3.30 but it won't handle my 3gb external drive. I was using dos 4.01 without any problems before, so I might just reinstall that. Besides, that os I have the original disks, license, and books too, like 3.30, but at least it'll handle my external fine.

I have been living off the external because the internal was so bad, and it finally got to the point where I could barely boot. But if this works out good, I might be able to live off the internal again.
 
DOS 3.30 won't handle drives over 30mb. Compaq DOS 3.3 is the only version that will. I've been using DOS 4.01 because of that very same reason too. Hope everything works well.
 
Hmm, I did the whole low level formatting procedure again, and while when it gets to sector 60, it does that re-seek again, it never marks it bad.

Is this something to worry about? It is reproducible on every format command, always stops at sector 60.
 
evildragon said:
Hmm, I did the whole low level formatting procedure again, and while when it gets to sector 60, it does that re-seek again, it never marks it bad.
Click to expand...
So we're talking about this happening during a low-level format.

With these old drives, at the low-level format level, there is no 'bad track' table. When the low-level format program marks a track as bad, the marking is done on the track itself. Therefore, each time you start a low-level format operation, the low-level format program has no idea about what lays ahead of it. The low-level format program is going to jump to cylinder 0 then go visit each track and attempt a format/verify operation on that track.

The exception to that would be if you inform the low-level format program up front of known defective tracks (as listed on the drive's 'defect track' sticker, or tracks that you know have gone defective since manufacture). Even so, the low-level format program is going to attempt to do something with that known defective track - such as a 'format bad track' operation.

evildragon said:
Is this something to worry about? It is reproducible on every format command, always stops at sector 60.
Click to expand...
When a DOS format is done later, DOS will attempt to read each sector in the partition. If it can't reliably read the sector, it will mark the corresponding blocks in the FAT as 'bad', and thus not use them.
 
evildragon said:
Is this something to worry about? It is reproducible on every format command, always stops at sector 60.
Click to expand...

The seek sound doesn't mean that the sector is already bad, but only that the head is having trouble reading it. In most cases that sector will become a defective one sometime...

I think the solution would be to code an application that reads all sectors and marks bad those that takes more than 2 seconds to read.
 
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