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Changing interleave.

L

Luke

Experienced Member
Joined
Apr 3, 2006
Messages
418
Location
Poland
Hello, how can I format drive with interleave = 2? My controller's low level format program:

A:\debug

-G=C800:0001

WX2 Format Revision 7.0 (C) Copyright Western Digital Corp. 1985
(AH) = Relative drive number ( 0 - 7 )
(AL) = Interleave factor ( 3 is standard )
press "y" to begin formatting drive C with interleave 90_

When I type G=C800:0005, interleave is 3.
 
I can't remember exactly how Debug works anymore, but you should be able to pull out an older DOS manual to get the specifics of the commands. A Google search might also work.

Basically you need to push the value you want into the low portion of the A register (AL) while preserving the drive ID in the high area (AH.)

The assembly language equivalent would be MOV AH,2h

You can probably use the debug (A)ssemble directive to do this or you can directly reference the registers with the -r directive. I can't remember if Debug understands AH/AL or if it will only deal with AX (the full 16 bit register.)

The real question, however, is why would you want to do this? If the drive is too slow for a 2 interleve you are going to turn it into a real pig by changing the value and the only way to fix it, of course, would be another low-level format.
 
This not work :( . I need it to format Segate ST-225, it cannot be formated with interleave = 3.
 
I have tried debug and it didn't work. ^Error... in debug there is MOV instruction, so I wrote mAL,2h :rolleyes: I have NASM assembler compilator, could you write small program for me?
 
Luke said:
I have NASM assembler compilator, could you write small program for me?
Click to expand...

Not likely. I'm deep in the bowels of way too many other things, sorry to say.

But keep plugging with debug. You should be able to do what you want in one way or another.

Best of luck!
 
Luke,

There are DOS programs designed for Western Digital hard drive controllers that might give you an easier way to set the desired interleave factor and low-level format the drive. Look for something like wdfmt, or check the SimTel archives.
 
WDFMT is for IDE-AT drives... I haven't found any utillity to low level format MFM drive.
 
My point is that there is software that does this already, and you should look for it at places like Simtel.

Just a small point of disagreement - WDFMT is not for IDE drives. IDE controllers/drives generally do not support low-level formatting using a generic program. The 16 bit controller and ST-225 certainly are MFM, and wdfmt did a fine job of formatting that drive.
 
I have 8bit controller and utillity don't see the hard drive, maybe it see but when click format system halt. I'am trying to format this drive again with interleave 3... how much time it could take?
 
This is from very fuzzy memory, but a good (i.e. few bad sectors) ST-225 should low level format in under 20 minutes.

It sounds like your setup might be locking up the computer somehow. Are you seeing drive activity when you click format? The drive activity light should be flashing and, if your ST-225 is typical, you should hear a light clicking noise as the heads advance.
 
I have formated it for 35 mins and i restarted computer... I think that is's broken up. It's quite loud and light is flashing only when I start computer and I'am formatting it, during it hear quiet rrrrrrrrrrrrr... rrrrrrrrrrrr... no 'clicking noise'. Propably heads are damaged, yes?
 
It sure does sound like a damaged drive. Heads, platters, stepper motor or who knows what.

Do you have another you can try in the same configuration?
 
Propably I'll get another ST-225 in next week, so I will check it with my controller and configuration. I have other MFM drivers that work correctly with it.
 
HD format

HD format

Hi Luke:

How's this HD format coming?

I'm wondering why you feel the need to change the interleave? The drive will function with any interleave that is used, altough it will be far more efficient with the correct interleave.

For those that might not be aware: Interleave is the spacing of the individual sectors within a particular track. It's purely a matter of efficiency. A "wrong" interleave will still work, it just might not work as fast the the "correct" interleave.

Here's why: If the sectors were written one after another (i.e. sector 1, then sector 2, then sector 3, etc.) the data would not be read or written efficiently. The computer was so slow that it would read a sector, process the sector, and by the time it was ready to read the next one in, it had already passed by the head.

So, the sectors were "interleaved", so that it might be, say, sector 1, 10, 20, 2, 11, 21, 3, 12, 22, etc. That way, when the computer was ready to read in the next sector, it was just coming under the head.

If the interleave is "wrong", the drive will still read and write properly, but it will have to wait one complete revolution to wait until the next sector came around again. So if the drive sectors were formatted in numerical order (sector 1, sector 2, sector 3, etc.) here's what would happen.

The computer would read sector 1, process it, and be ready for sector 2. But the next sector to pass under the head is actually sector 3, so it would have to wait until sector 2 came around again.

All that the incorrect interleave does is waste time, because the drive is always having to wait until the next-desired sector comes around again!

Now, if you're having trouble formatting, there must be another problem, other than interleave. But you said that the drive was "quiet" during formatting. That should be OK, since, IIRC, there wasn't much head noise until towards the end of the formatting process.

If you pick the wrong interleave (i.e. an inefficient one), the actual formatting won't take any longer, since the entire track is written at once. But the verify process will take a long time, because that is done like a standard read.

The rule for interleave was, if you're not sure of the correct number, always to use a higher number instead of a lower one. So, if you think it ought to be 3, then using 4 or 5 wouldn't hurt, and would not be as bad as using 1 or 2 when it should be 3.

The format program itself is in the HD controller BIOS (not the computer BIOS), so there are different variations, depending on the brand and version of the HD controller.

Most of them allowed you to enter the desired number. IIRC, they would show each current setting, and allow you to enter a new one. There was no prompt, and maybe not even a blinking cursor, so try to enter a number on the line labeled "Interleave".

You could also look for a formatting program on the web. Seagate and Western Digital used to ship an OEM version of OnTrack software with their drive, and it was used to do diagnostics and things like setting the optimum interleave. Maybe you could find one of those disks? They came in a blue & white floppy disk folder. (I threw out tons of these back in the day, since I only needed one, but I got one with each drive that I installed!)

In your case, I'd start the format, and go to bed. Let it run all night and see what happens!

I hope all of this helps!
 
Sticktion!

Sticktion!

Hi Terry:

[Stiction has a tendancy to glue the ST-225's heads to the platters, only to rip them from thier mountings when the drive is powered-up.]

I never had drive heads "ripped from their mountings" due to this phenomenon, but I did have drives that would not spin up.

The "sticktion" Terry's talking about is the tendency for the drive heads to "stick" to the platter once the drive spins down and stays off for a period of time.

Seagate ST-225s had this problem often, though usually only when the drive had been off for a week or more.

The symptom was a drive that would not spin up. Often people would have this problem, bring the computer in for service, and when we turned it on, it would work fine. We'd write up a "no problem found" ticket, and send them home.

The reason for this is that the computer would get jostled around when the customer brought it in (even when they wrapped the computer in blankets and seat-belted them into the back seat-- as people often did!), and the heads would become "unstuck".

Seagate had a "fix" for these stuck drives, though they didn't tell the general public. The "fix" was as follows:

1) Remove the drive from the computer.
2) Put the drive back in the original shipping foam, and into the original box.
3) Seal the box with packing tape, as if you were going to ship it.
4) Carry the box to a clean, uncarpeted floor.
5) Lift the box three feet above the floor.
6) Drop the box, ONE TIME ONLY.
7) Remove the drive from the box, and re-install it in the computer.
8) If the problem persists, call Customer Service to obtain an RMA number.
 
I haven't got another ST-255, but I have 2 drives that works fine with this controller. Problem is that Seagate utility and Western Digital's don't see the drive :(. No matter - if I leave it formatting for 5 min. or 35 min. FDisk can make partition but I can't format it (only ~3 cylinders on both heads). Seem like something is wrong with step motor.
 
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