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810 format/write error


ebiguy

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Hi,

 

I have a 810 which is working very well when reading disks.

I can boot and games or DOSes are loading fine.

 

But when I try to format a disk in single density using DOS 2.0S, I get error 10K (letter K is written in reverse video !!!).

I tried many disks and there is always the same error.

Of course, I also already cleaned the head.

 

First question: I was not aware of this error (10K). Any information about it ?

 

Second question: I already checked in the troubleshooting section of the 810 FSM but I am not a hardware guy.

So I ask here if someone has already experienced this behavior and how it was fixed.

 

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Error 10K happens when the format command is failed by the drive. It seems there is some strange code in DOS 2.0S that checks specifically for the device error case (Y=$90) and tries to report the first bad sector as an error code, but many drives don't report a bad sector list and DUP just ends up printing 10K for $FF.

 

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Thanks!

At least now the mystery of 10K is solved.

I get this error code with both a genuine DOS 2.0S and a genuine DOS 2.5.

I tried also under SDX but the error codes are not displayed (only "formatting error" or something like that).

Could you remind me where the $90 comes from ?

Is it from a Status command sent after the Format command or from the returned buffer from the Format command ?

I don't think it will help me make the drive works but I like to understand the whole thing.

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$90 is 144 decimal which is the generic error a peripheral returns when it can't process a command.

Other examples of it returning are writing to write protected disk or accessing a drive when the door's open or no disk is present.

 

The 128 byte buffer returned when formatting a disk - from memory should contain a bunch of 2-byte bad sector numbers terminated with $FF,$FF.

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Y=$90 is the status code returned by the SIO routines in the OS when a peripheral fails a command with Error ($45) instead of Complete ($43) in the SIO protocol sequence. This occurs for errors that only happen after the peripheral has started a long operation. It is distinct from Y=$8A, which is returned for a NAK ($4E), which is returned for command errors or data frame checksum errors that are detected quickly.

 

If the drive successfully reads or writes disks but can't format them, then I wonder if the problem might be the connection from the RIOT to the index pulse (IP) input on the floppy drive controller. The 810 doesn't use a real index pulse, it fakes it under RIOT control. For normal reads or writes, this is only needed to force the FDC to time out when a sector doesn't exist, and so the drive can probably work without it. When formatting a disk, though, the FDC requires index pulses since the Write Track command runs from index to index.

 

 

 

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On 2/9/2020 at 7:14 PM, ebiguy said:

I have a 810 which is working very well when reading disks.

I can boot and games or DOSes are loading fine.

 

But when I try to format a disk in single density using DOS 2.0S, I get error 10K (letter K is written in reverse video !!!).

I tried many disks and there is always the same error.

Of course, I also already cleaned the head.

 

You can't format but you can write to disks, or you can't write at all, not even to disks already formatted?

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sometimes it may be the type of floppy you are using, I have 2 1050's sometimes if I can't format a disk in one drive

the other does it fine.

 

It may be that one is US Doubler and the other a Happy 1050, so maybe the format routines handle format anomalies

differently and retry's are successful on one but not the other.

 

I also have some disks, brand new (although had them many years) that will not format in either drive.

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Thank you to all who answered with ideas/questions

I did not try to write a disk. Only format command. So I made some more tests

- write does not work: Error 144. For example, I try to write MEM.SAV and it takes exactly 6 seconds to get the error 144. I can hear the head moving during these 6 seconds.

- format still returns error 10K but there are many retries. I can also hear the head moving and at some point the famous Brrr to force a restore to track 0 and again head is moving and then Brrr which occurs 5 or 6 times).

The time between the format command and the error 10K is 65 seconds.

This is quite strange because if there was an an issue with the write protect sensor, it should return almost immediately an error 144 for both write and format operations.

Note that when I say that head is moving, I don't see it (case is closed) but I hear the usual sound when the head moves to the next track.

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4 hours ago, ebiguy said:

This is quite strange because if there was an an issue with the write protect sensor, it should return almost immediately an error 144 for both write and format operations.

I was going to ask if it might be the write protect sensor - but you already answered.. It sounds like it's going through the motions of stepping from track 0 through to track 39 before giving you the error. I wonder if it is even actually erasing the disk. Please try formatting a disk in another known good drive. Copy something small to it. Now format that disk in the problem drive. Even after it fails, see if the disk has actually been erased, or if the original content is still readable.

 

Also, please compare the "look" of your 810 formatting compared to this video I made of an 810 with stock Atari revision C ROM:

What you can see here is the drive starting from it's idle position at track 39. When the format command is issued it jumps to track 0, and begins formatting each track from 0 to 39. Then it does the READ verify backwards stepping from track 39 to track 0. If you get the format error at the beginning then the drive can't even read where the track index mark is during the initial format. if it errors anywhere after it starts seeking backwards, it can't read the sector headers or data.

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If the drive can read without problems, it cannot write at all, and you confirmed it is not the write protect, then it is probably not the track 0 sensor, not the seek, not the motor, not the index. It is something in the actual write channel and could be anywhere from the FDC to the head. Sounds difficult to solve without a scope and replacement parts.

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I tried to format several disks.

All the disks I tried in this 810 were formatted in a 1050 without any error.

When formatting on the 810, I have 2 results depending on the disks:

- either the format gives the error 10K.

- or the format almost manage to work.

By almost, I mean that the head goes from track 39 to track 0 then go step by step to track 39 to format the disk.

But the comparison with the above video stops there.

In my drive, the ROM does not go backwards step by step to read each sectors to find bad ones.

Instead it goes straight to the middle of the disk and tries to write sectors.

I can also see the commands sent by the Atari in RespeQt:

 

[Disk 1] command: $21, aux: $0054 ignored: Format Single Density Disk
[Disk 1] command: $57, aux: $0168 ignored: Write Sector (with verify) [x8]

And then I get the error 144.

 

Then I get the disk back in the 1050.

Initially, there was a DOS 2.0S on the disk (before format in the 810).

When I look at the directory, the 2 DOS files are still there and I can copy the content to E: and see that the file content is intact.

It means that the format command did nothing even though it went through each track.

 

Looking at the commands sent by the Atari, I think the DOS thought that the format succeeded.

Otherwise no Write Sector command would have been issued.

 

There are many things I don't understand here:

- why does the format command succeed

- why does the ROM end the format command without checking all the sectors backwards.

- why does the write do nothing on the disk (problem with the write gate?)

 

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What firmware do you have in the drive? Atari and Happy 810 firmware should do two-pass format and verify, but the 810 Archiver does single-pass with interleaved format and verify per track.

 

One thing you could try is formatting a disk as enhanced density on the 1050, then trying to reformat it on the 810. Unlike the write verify command, the format command on the 810 doesn't actually check the data it reads back on the verify pass, it just checks that the sector can be read with a valid CRC. It's possible that the drive is not actually writing anything on the format pass, then verifying the existing sectors. The subsequent writes then fail because the write-with-verify command does actually check the read data against what was written. If I'm right, then trying to format over an enhanced density disk should fail on the format because the verify pass won't be able to read the MFM sectors on the disk.

 

Also, if this is the case, then editing DOS to turn write verify off should also change the behavior: it should get farther or even complete the write "successfully."

 

Edited by phaeron
(add write verify test)
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1 hour ago, phaeron said:

What firmware do you have in the drive?

Hi Phaeron,

I had the same idea and I booted with the The Super Archiver disk inside the drive and bingo, the drive contains The Chip.

I made a dump of the ROM (through SIO, not by removing the EPROM) and I found that there is a pirate ROM (code is 1234 and the copyright has been replaced by $FF)

That explains why the formatting process was not the same.

Then I used Super Archiver to copy a disk to the DOS 2.0S disk.

If I set V- (verify Off) in Super Archiver, there is no error (read OK and write OK).

But at the end of the day, I still have my DOS disk intead of the new content.

If I set V+ (Verify On) in Super Archiver then it fails on the first track.

I also tried what you suggested: formatting a disk in enhanced density and you are right: this time, the format using DOS 2.0S fails on the first track (after many retries).

And the result is an error 10K.

So, all of this clearly shows that nothing is written to the disk.
Any idea what part of the drive is failing: which board, which chip or which component?

I have the drive with the data separation board.

Edited by ebiguy
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Good find on the Archiver mod.

 

Have you tried swapping the mech into another working 810?

 

Also, try swapping the side board from a working 810 into this drive, since the side board has to be modified to support a 4KB EPROM for an Archiver... That would reduce the problem areas to the rear power board or the top analog board.

 

The fact you mention the Archiver ROM has been modified as you found (open code 1234, copyright replaced with $FF's) it's possible something else has been broken by whomever edited it, or 'write protect' function has been altered to work differently. You could try installing an EPROM with a known-good image, ie this one I posted: https://atariage.com/forums/topic/275134-another-unknown-eprom/?tab=comments#comment-4432031

 

Could you post a dump of your EPROM? It would be interesting to try running with full drive emulation in Altirra to see if by chance the problem can be replicated there.

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Thank you for your answer,

 

8 hours ago, Nezgar said:

try swapping the side board from a working 810 into this drive

I will do that.

 

8 hours ago, Nezgar said:

it's possible something else has been broken by whomever edited it

No chance.

Do you really think that, back in the days, someone put a Chip which could not write to a disk?

The probability is more towards a dead component (capacitor or whatever - I am not a hardware guy).

But, here is the dump. Same as the standard ROM except open code and copyright

chip1234.rom

 

PS: reading the thread you mentioned, I answered an old question you were asking.

 

Edited by ebiguy
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I swapped the board on top of the drive mech with another 810 and now it works.

So there is something with this board.

 

Any advice to either

- diagnose the issue

- or send the board to someone who can repair it (in Europe)

- or buy a new one (still in Europe because buying from US makes the price crazy with shipping and customs).

 

EDIT: Strangely, I have several 810 Service manuals (PDF) and none of them covers this board.

I guess there exists a manual describing it.

Edited by ebiguy
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15 hours ago, ebiguy said:

No chance.

Do you really think that, back in the days, someone put a Chip which could not write to a disk?

The probability is more towards a dead component (capacitor or whatever - I am not a hardware guy).

But, here is the dump. Same as the standard ROM except open code and copyright

hehe, for sure it was a longshot, heavy speculation while trying to think what else could be wrong. :D Thanks for the dump. I agree unlikely if those are the only changes.

 

13 hours ago, ebiguy said:

I swapped the board on top of the drive mech with another 810 and now it works.

So there is something with this board.

Excellent you've narrowed it down to the analog board!

 

13 hours ago, ebiguy said:

Strangely, I have several 810 Service manuals (PDF) and none of them covers this board.

I guess there exists a manual describing it.

 

Maybe the Rev 2 810 Field Service Manual?
http://www.atarimania.com/documents/Atari_810_Disk_Drive_Service_Manual_Rev_2.pdf

There is a troubleshooting flow chart for the 810 Analog drive on PDF page 138 - indicates for a write fail go to 8B-22 (PDF page 144) which has some suggestions:
- "Is there 0.8V on pin 12 of A106?" No: replace phototransistor (you previously indicated write protect sensor seems OK), Yes: replace in order: A106, Z103, A105

Cheers-N

 

 

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7 hours ago, Nezgar said:

There is a troubleshooting flow chart for the 810 Analog drive on PDF page 138 - indicates for a write fail go to 8B-22 (PDF page 144) which has some suggestions:
- "Is there 0.8V on pin 12 of A106?" No: replace phototransistor (you previously indicated write protect sensor seems OK), Yes: replace in order: A106, Z103, A105

I already have this manual (I think I have them all).

The "new" analog board write troubleshooting is on page 8C-28 page 194 but it does not help as it tell me again to replace A106, Z103, A105.

But these components are NOT on the analog board and the problem is solved when I swap this analog board.

So I expect a solution which suggest to replace something on this board.

Right now I am stuck.

 

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Had a look at the circuit, if you have a scope, you could check for data coming from the FDC on pin 31 (this is the write data)

this feeds a 4031 (dual D type flip flop) on pin 11 (clk).

 

If the signal is there, check the output on pins 13 and 12 on the flip flop have data.

 

If there's no output, it could be the 4031 is duff, but there is also another chip Z103F which resets the flip flop, check if

pins 4 and 10 are LOW on the flip flop, if it's high, the flip flop won't clock.

 

Check pin 13 of Z103F, this needs to be HIGH ( I would assume this is ok as the drive works for reading )

810_2_1.gif

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Thank you very much for your help.

 

6 hours ago, TGB1718 said:

Had a look at the circuit, if you have a scope, you could check for data coming from the FDC on pin 31 (this is the write data)

this feeds a 4031 (dual D type flip flop) on pin 11 (clk).

Arg, as I am not a hardware guy, I have no scope.

 

BTW, the 810 schematics you put in your message does not include the new analog board on top of the drive mech.

Here are some pictures of it (one for the overall view and 3 for a detailled view).

You will see that all the components have a number in the range 200-299. No components in the range 100-199 (for example R208, C202,...)

And they do not appear on Sobola's schematics.

And I know that it is one of the components in this analog board that fails because, if I swap with another one, everything works well.

 

Overall view

IMG_0503.thumb.JPG.b241b28b7505147b0f07ffea8f7b45c8.JPG

Left part

IMG_0504.thumb.JPG.0fbfb1fb74ca985882547bed7f0d06a0.JPG

Middle part

IMG_0505.thumb.JPG.5af4245d7d0e0a4f0c482dfd3a656920.JPG

Right part

IMG_0506.thumb.JPG.82ef0518d853219e90e85fd3b471cb86.JPG

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9 hours ago, ebiguy said:

BTW, the 810 schematics you put in your message does not include the new analog board on top of the drive mech.

Nezgar included a link to the Rev.2 of the 810 Field Service Manual in post #15(correction: post#18). The section on the analog board starts on page 125, and the diagnostic flowchart section starts on page 133.

Edited by BillC
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1 hour ago, BillC said:

The section on the analog board starts on page 125, and the diagnostic flowchart section starts on page 133.

Yes I saw that.

I think the "Fail Format Troubleshooting" is for me but I don't have an oscilloscope and all the tests of these sections are based on this tool.

Or I can try to replace all components mentioned in these 3 pages in the hope that the problem is solved.

Maybe that's the way to go.

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Looking at the parts list, the IC's on that board are common enough and shouldn't cost much and for a bonus they are all in sockets

so a good place to start

 

Shame that the manual is a pretty poor copy, its very hard to read the circuit diagram

Edited by TGB1718
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