Need an 8280 formatted 8" disk

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Need an 8280 formatted 8" disk

Rob Clarke
Gents,

I'm desperately in need of a known good 8" floppy formatted on an 8280.
After 18 months of occasional work, I now have my 8280 up and running,
or at least I think I do. DOS board is up and running, the drives are
refurbished and behaving, and I have a good power source. I can trace
signals all the way from the FDC to the read/write heads and back again.

Nevertheless, using the 2 no-name 8" disks I have, the format fails with
an error 21 on track 0, sector 1 every time. So, to track the fault down
it would really help to have a good disk. Either I can post one of my
disks to someone or, if you hace a spare 8" disk, I'd gladly compensate
for that and time, postage etc...

Regards, Rob


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Re: Need an 8280 formatted 8" disk

william degnan


On Mon, Feb 13, 2017 at 7:54 AM, Rob Clarke <[hidden email]> wrote:
Gents,

I'm desperately in need of a known good 8" floppy formatted on an 8280. After 18 months of occasional work, I now have my 8280 up and running, or at least I think I do. DOS board is up and running, the drives are refurbished and behaving, and I have a good power source. I can trace signals all the way from the FDC to the read/write heads and back again.

Nevertheless, using the 2 no-name 8" disks I have, the format fails with an error 21 on track 0, sector 1 every time. So, to track the fault down it would really help to have a good disk. Either I can post one of my disks to someone or, if you hace a spare 8" disk, I'd gladly compensate for that and time, postage etc...

Regards, Rob




what series of commands are you using to attempt to format a disk on the drive?   I assume you're doing the standard commands:

header "disknamehere", d0, i01 

(assuming you have a disk in drive 0 of an 8280 drive). NOTE: i01 assigns the identification name/number; 01” can be substituted for any two alpha characters.   Once you attempt to format a disk, change the identification number each time.

Bill

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Re: Need an 8280 formatted 8" disk

william degnan


header "disknamehere", d0, i01 

<snip>

and  header "disknamehere", d1, i01   (to format a disk in the other drive).
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Re: Need an 8280 formatted 8" disk

Rob Clarke

Just using the pre basic-4 commands: open15,8,15,"n0:disknamehere,01"


On 13/02/2017 14:16, william degnan wrote:


header "disknamehere", d0, i01 

<snip>

and  header "disknamehere", d1, i01   (to format a disk in the other drive).

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Re: Need an 8280 formatted 8" disk

william degnan


On Mon, Feb 13, 2017 at 8:35 AM, Rob Clarke <[hidden email]> wrote:

Just using the pre basic-4 commands: open15,8,15,"n0:disknamehere,01"


On 13/02/2017 14:16, william degnan wrote:


header "disknamehere", d0, i01 

<snip>

and  header "disknamehere", d1, i01   (to format a disk in the other drive).


see what header does.  Should not make any difference but I am curious.  When you format and it fails, do you power off/on each time?  Just curious.  Also before you format what returns when you enter 

?ds$ 

This will tell you if the processor board of the disk drive is OK or not. The response you want will be something like: "73, cbm dos v. 2.x"   (or whatever version).  

Bill
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Re: Need an 8280 formatted 8" disk

Ethan Dicks
In reply to this post by Rob Clarke
On Mon, Feb 13, 2017 at 7:54 AM, Rob Clarke <[hidden email]> wrote:
> I'm desperately in need of a known good 8" floppy formatted on an 8280.

An 8280?  Nice.  That's one of those devices I've wanted to fiddle
with for the fun of it (but wouldn't want to have as my primary
storage device).

> After 18 months of occasional work, I now have my 8280 up and running, or at
> least I think I do. DOS board is up and running, the drives are refurbished
> and behaving, and I have a good power source. I can trace signals all the
> way from the FDC to the read/write heads and back again.

Sounds great.

> Nevertheless, using the 2 no-name 8" disks I have, the format fails with an
> error 21 on track 0, sector 1 every time. So, to track the fault down it
> would really help to have a good disk. Either I can post one of my disks to
> someone or, if you hace a spare 8" disk, I'd gladly compensate for that and
> time, postage etc...

I do not have any 8280-formatted media (or a drive), but... I read
that the drive supports two formats: native ~500K GCR and standard
250K MFM "IBM 3740" format.  If you have a working 8" drive on some
other platform, or even just have any DEC RX01 media, you might be
able to start out reading blocks into drive RAM and pulling bytes out
with M-R, as a test of non-write portions of the drive.

I'd also consider writing some BASIC code to try to read different
tracks to make sure the heads dance appropriately.  Without good
media, of course the actual reads will fail, but the positioner should
do the right thing.

In case there is a problem with the heads, is the drive mech of a type
that can be tested on another platform?  (Tandon TM848, for example,
which the photo resembles)

If someone can send you an 8280-formatted disk, that's great (not sure
how many of those are out there), but I think there are some partial
tests you can do with more common media.

-ethan

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Re: Need an 8280 formatted 8" disk

william degnan


If someone can send you an 8280-formatted disk, that's great (not sure
how many of those are out there), but I think there are some partial
tests you can do with more common media.

-ethan

       Message was sent through the cbm-hackers mailing list

how many 8280's are even in existence?  Being a millionaire is easy, first get a million dollars and then ...  Same goes for the 8280....formatting an 8280 is easy, first get an 8280 drive and then ...

I just think it's ironic you have this drive and no disks.  I have piles of new 8" disks and not a single 8280 :-)

b
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Re: Need an 8280 formatted 8" disk

Charlie
I have an 8280.  Believed to be working.  I might be able to help you.  Charlie
 
Sent: Monday, February 13, 2017 10:38 AM
Subject: Re: Need an 8280 formatted 8" disk
 


If someone can send you an 8280-formatted disk, that's great (not sure
how many of those are out there), but I think there are some partial
tests you can do with more common media.

-ethan

       Message was sent through the cbm-hackers mailing list
 
how many 8280's are even in existence?  Being a millionaire is easy, first get a million dollars and then ...  Same goes for the 8280....formatting an 8280 is easy, first get an 8280 drive and then ...
 
I just think it's ironic you have this drive and no disks.  I have piles of new 8" disks and not a single 8280 :-)
 
b
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Re: Need an 8280 formatted 8" disk

william degnan


On Mon, Feb 13, 2017 at 9:48 AM, Charlie <[hidden email]> wrote:
I have an 8280.  Believed to be working.  I might be able to help you.  Charlie
 
Sent: Monday, February 13, 2017 10:38 AM

I just think it's ironic you have this drive and no disks.  I have piles of new 8" disks and not a single 8280 :-)
 
b


What if.....Could it be possible to use a 34-50 pin drive cable adapter by tricking a newer computer (i.e.Pentium III) into thinking it's writing to a 1.2M 5 1/4" when it's actually a 8" disk? Assuming it already had the ability to create usable on a 8250 5 1/4" disks.   Could one make an 8" for the 8280 in the same way using a catweasel or similar?  

I bet there is a combo of software and hardware that could read / write to an 8" disk where the computer thinks is writing to a 1.2M HD disk.

Just speculating.

b
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Re: Need an 8280 formatted 8" disk

Charlie
I have an 8280 drive thought to be working.  Perhaps I can help, Charlie
 
Sent: Monday, February 13, 2017 11:37 AM
Subject: Re: Need an 8280 formatted 8" disk
 
 
 
On Mon, Feb 13, 2017 at 9:48 AM, Charlie <[hidden email]> wrote:
I have an 8280.  Believed to be working.  I might be able to help you.  Charlie
 
Sent: Monday, February 13, 2017 10:38 AM
 
I just think it's ironic you have this drive and no disks.  I have piles of new 8" disks and not a single 8280 :-)
 
b
 
 
What if.....Could it be possible to use a 34-50 pin drive cable adapter by tricking a newer computer (i.e.Pentium III) into thinking it's writing to a 1.2M 5 1/4" when it's actually a 8" disk? Assuming it already had the ability to create usable on a 8250 5 1/4" disks.   Could one make an 8" for the 8280 in the same way using a catweasel or similar? 
 
I bet there is a combo of software and hardware that could read / write to an 8" disk where the computer thinks is writing to a 1.2M HD disk.
 
Just speculating.
 
b
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Re: Need an 8280 formatted 8" disk

Rob Clarke

That would be great Charlie, I'll contact you off list.


On 13/02/2017 16:43, Charlie wrote:
I have an 8280 drive thought to be working.  Perhaps I can help, Charlie
 
Sent: Monday, February 13, 2017 11:37 AM
Subject: Re: Need an 8280 formatted 8" disk
 
 
 
On Mon, Feb 13, 2017 at 9:48 AM, Charlie <[hidden email]> wrote:
I have an 8280.  Believed to be working.  I might be able to help you.  Charlie
 
Sent: Monday, February 13, 2017 10:38 AM
 
I just think it's ironic you have this drive and no disks.  I have piles of new 8" disks and not a single 8280 :-)
 
b
 
 
What if.....Could it be possible to use a 34-50 pin drive cable adapter by tricking a newer computer (i.e.Pentium III) into thinking it's writing to a 1.2M 5 1/4" when it's actually a 8" disk? Assuming it already had the ability to create usable on a 8250 5 1/4" disks.   Could one make an 8" for the 8280 in the same way using a catweasel or similar? 
 
I bet there is a combo of software and hardware that could read / write to an 8" disk where the computer thinks is writing to a 1.2M HD disk.
 
Just speculating.
 
b

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Re: Need an 8280 formatted 8" disk

Rob Clarke
In reply to this post by william degnan

I have 8" disks, just not one that is formatted, so I can't isolate the problem to reading / writing, or media.


On 13/02/2017 15:38, william degnan wrote:


If someone can send you an 8280-formatted disk, that's great (not sure
how many of those are out there), but I think there are some partial
tests you can do with more common media.

-ethan

       Message was sent through the cbm-hackers mailing list

how many 8280's are even in existence?  Being a millionaire is easy, first get a million dollars and then ...  Same goes for the 8280....formatting an 8280 is easy, first get an 8280 drive and then ...

I just think it's ironic you have this drive and no disks.  I have piles of new 8" disks and not a single 8280 :-)

b

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Re: Need an 8280 formatted 8" disk

Rob Clarke
In reply to this post by Ethan Dicks
Thanks Ethan, I have no other 8" drives other than this one, and only 2
disks of unknown status.

Yes, I've considered writing such a program to step the drive etc, but
as the ROM of the 8280 is not documented and is AFAIK, unique in using a
WD FD1797B-02 controller, I simply don't know how without a large amount
of effort to disassemble the ROMS.

Rob

On 13/02/2017 15:08, Ethan Dicks wrote:

> On Mon, Feb 13, 2017 at 7:54 AM, Rob Clarke <[hidden email]> wrote:
>> I'm desperately in need of a known good 8" floppy formatted on an 8280.
> An 8280?  Nice.  That's one of those devices I've wanted to fiddle
> with for the fun of it (but wouldn't want to have as my primary
> storage device).
>
>> After 18 months of occasional work, I now have my 8280 up and running, or at
>> least I think I do. DOS board is up and running, the drives are refurbished
>> and behaving, and I have a good power source. I can trace signals all the
>> way from the FDC to the read/write heads and back again.
> Sounds great.
>
>> Nevertheless, using the 2 no-name 8" disks I have, the format fails with an
>> error 21 on track 0, sector 1 every time. So, to track the fault down it
>> would really help to have a good disk. Either I can post one of my disks to
>> someone or, if you hace a spare 8" disk, I'd gladly compensate for that and
>> time, postage etc...
> I do not have any 8280-formatted media (or a drive), but... I read
> that the drive supports two formats: native ~500K GCR and standard
> 250K MFM "IBM 3740" format.  If you have a working 8" drive on some
> other platform, or even just have any DEC RX01 media, you might be
> able to start out reading blocks into drive RAM and pulling bytes out
> with M-R, as a test of non-write portions of the drive.
>
> I'd also consider writing some BASIC code to try to read different
> tracks to make sure the heads dance appropriately.  Without good
> media, of course the actual reads will fail, but the positioner should
> do the right thing.
>
> In case there is a problem with the heads, is the drive mech of a type
> that can be tested on another platform?  (Tandon TM848, for example,
> which the photo resembles)
>
> If someone can send you an 8280-formatted disk, that's great (not sure
> how many of those are out there), but I think there are some partial
> tests you can do with more common media.
>
> -ethan
>
>         Message was sent through the cbm-hackers mailing list


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Re: Need an 8280 formatted 8" disk

Rob Clarke
In reply to this post by william degnan

THanks Bill, I am reasonably familar with Commodore DOS. The communication between the computer and the drive is fine, and returns "73 CBM DOS V3.0"

At the moment it's actuallly been driven from a 64 with an DAMS IEEE card, simply because it takes up less desk space. I will try a PET or CBM-II but I would be very surprised if that's the issue.

Rob

On 13/02/2017 14:54, william degnan wrote:


On Mon, Feb 13, 2017 at 8:35 AM, Rob Clarke <[hidden email]> wrote:

Just using the pre basic-4 commands: open15,8,15,"n0:disknamehere,01"


On 13/02/2017 14:16, william degnan wrote:


header "disknamehere", d0, i01 

<snip>

and  header "disknamehere", d1, i01   (to format a disk in the other drive).


see what header does.  Should not make any difference but I am curious.  When you format and it fails, do you power off/on each time?  Just curious.  Also before you format what returns when you enter 

?ds$ 

This will tell you if the processor board of the disk drive is OK or not. The response you want will be something like: "73, cbm dos v. 2.x"   (or whatever version).  

Bill

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Re: Need an 8280 formatted 8" disk

Ethan Dicks
In reply to this post by Rob Clarke
On Mon, Feb 13, 2017 at 10:54 AM, Rob Clarke <[hidden email]> wrote:
> Thanks Ethan, I have no other 8" drives other than this one, and only 2
> disks of unknown status.

That does make it harder.

> Yes, I've considered writing such a program to step the drive etc, but as
> the ROM of the 8280 is not documented and is AFAIK, unique in using a WD
> FD1797B-02 controller, I simply don't know how without a large amount of
> effort to disassemble the ROMS.

I wasn't suggesting going to that point, rather a simple BASIC program
to do a "B-R" command for blocks on different tracks which _should_
cause the drive to seek, then fail as the media under the head lacked
the correct format to produce meaningful results.  So it _would_
"fail", but the head would at least move around.

>> In case there is a problem with the heads, is the drive mech of a type
>> that can be tested on another platform?  (Tandon TM848, for example,
>> which the photo resembles)

I looked into ftp://www.zimmers.net/pub/cbm/schematics/drives/old/8280/index.html
 It _is_ a Tandon TM-848.  That is an easy one to hook up to a
"modern" machine, and for reads, you wouldn't need a "TG43" signal
generator (though this, from John Wilson, would take care of
everything including 50 pin<->34 pin wiring
http://www.dbit.com/fdadap.html)  If you did pull one of the drives
from the 8280, it could be hooked up to a PC and used as an 8" drive -
there are formatting programs, etc., out there for such use.  this
would only get you the IBM 250K MFM format, but that's supposed to be
supported on the 8280, so I _think_ one would do OPEN
15,8,15,"N0:MYDISK" to not format the media, but write out a BAM and
directory track).  A valid but admittedly intermediate test to
formatting the whole thing.

Oh... and since it's a dual drive, I'd also consider OPEN
15,8,15,"N1:MYDISK,XX" and if that failed the same way, I would
probably proceed under the expectation that both drive mechs are
probably not faulty in the same way.

Sounds like you have someone to send you an 8280 disk so you may be
all set, but I'd be impatient enough to at least fiddle with something
to read blocks on different tracks just to ensure the FD1797 FDC is at
least nominally happy.  Of course that won't test read/write and data
sep circuits or the TM848 heads, but it would test everything up to
that point.

-ethan

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Re: Need an 8280 formatted 8" disk

Mike Stein
You might find something of interest here:
http://www.retrotechnology.com/herbs_stuff/s_drives_howto.html

----- Original Message -----
From: "Ethan Dicks" <[hidden email]>
To: <[hidden email]>
Sent: Monday, February 13, 2017 11:33 AM
Subject: Re: Need an 8280 formatted 8" disk


> On Mon, Feb 13, 2017 at 10:54 AM, Rob Clarke <[hidden email]> wrote:
>> Thanks Ethan, I have no other 8" drives other than this one, and only 2
>> disks of unknown status.
>
> That does make it harder.
>
>> Yes, I've considered writing such a program to step the drive etc, but as
>> the ROM of the 8280 is not documented and is AFAIK, unique in using a WD
>> FD1797B-02 controller, I simply don't know how without a large amount of
>> effort to disassemble the ROMS.
>
> I wasn't suggesting going to that point, rather a simple BASIC program
> to do a "B-R" command for blocks on different tracks which _should_
> cause the drive to seek, then fail as the media under the head lacked
> the correct format to produce meaningful results.  So it _would_
> "fail", but the head would at least move around.
>
>>> In case there is a problem with the heads, is the drive mech of a type
>>> that can be tested on another platform?  (Tandon TM848, for example,
>>> which the photo resembles)
>
> I looked into ftp://www.zimmers.net/pub/cbm/schematics/drives/old/8280/index.html
> It _is_ a Tandon TM-848.  That is an easy one to hook up to a
> "modern" machine, and for reads, you wouldn't need a "TG43" signal
> generator (though this, from John Wilson, would take care of
> everything including 50 pin<->34 pin wiring
> http://www.dbit.com/fdadap.html)  If you did pull one of the drives
> from the 8280, it could be hooked up to a PC and used as an 8" drive -
> there are formatting programs, etc., out there for such use.  this
> would only get you the IBM 250K MFM format, but that's supposed to be
> supported on the 8280, so I _think_ one would do OPEN
> 15,8,15,"N0:MYDISK" to not format the media, but write out a BAM and
> directory track).  A valid but admittedly intermediate test to
> formatting the whole thing.
>
> Oh... and since it's a dual drive, I'd also consider OPEN
> 15,8,15,"N1:MYDISK,XX" and if that failed the same way, I would
> probably proceed under the expectation that both drive mechs are
> probably not faulty in the same way.
>
> Sounds like you have someone to send you an 8280 disk so you may be
> all set, but I'd be impatient enough to at least fiddle with something
> to read blocks on different tracks just to ensure the FD1797 FDC is at
> least nominally happy.  Of course that won't test read/write and data
> sep circuits or the TM848 heads, but it would test everything up to
> that point.
>
> -ethan
>
>       Message was sent through the cbm-hackers mailing list

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Re: Need an 8280 formatted 8" disk

Mike Stein
In reply to this post by Rob Clarke
Hi Rob,

Can't help you with a formatted disk but if you have trouble finding blanks once you get things sorted, let me know.

Note that single and double-sided disks have the index hole in different locations; most double-sided drives including the TM-848 have two sensors and can use both types, but it's something to keep in mind just in case.

m

----- Original Message -----
From: "Rob Clarke" <[hidden email]>
To: <[hidden email]>
Sent: Monday, February 13, 2017 7:54 AM
Subject: Need an 8280 formatted 8" disk


> Gents,
>
> I'm desperately in need of a known good 8" floppy formatted on an 8280.
> After 18 months of occasional work, I now have my 8280 up and running,
> or at least I think I do. DOS board is up and running, the drives are
> refurbished and behaving, and I have a good power source. I can trace
> signals all the way from the FDC to the read/write heads and back again.
>
> Nevertheless, using the 2 no-name 8" disks I have, the format fails with
> an error 21 on track 0, sector 1 every time. So, to track the fault down
> it would really help to have a good disk. Either I can post one of my
> disks to someone or, if you hace a spare 8" disk, I'd gladly compensate
> for that and time, postage etc...
>
> Regards, Rob
>
>
>       Message was sent through the cbm-hackers mailing list

       Message was sent through the cbm-hackers mailing list
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Re: Need an 8280 formatted 8" disk

Rob Clarke
In reply to this post by Ethan Dicks

> I wasn't suggesting going to that point, rather a simple BASIC program
> to do a "B-R" command for blocks on different tracks which _should_
> cause the drive to seek, then fail as the media under the head lacked
> the correct format to produce meaningful results.  So it _would_
> "fail", but the head would at least move around.
Good plan, I didn't think of that. I just tried it with B-R and the
appears to step up and down correctly, but of course also fails with a
read error.

> I looked into
> ftp://www.zimmers.net/pub/cbm/schematics/drives/old/8280/index.html
>   It _is_ a Tandon TM-848.  That is an easy one to hook up to a
> "modern" machine, and for reads, you wouldn't need a "TG43" signal
> generator (though this, from John Wilson, would take care of
> everything including 50 pin<->34 pin wiring
> http://www.dbit.com/fdadap.html)  If you did pull one of the drives
> from the 8280, it could be hooked up to a PC and used as an 8" drive -
> there are formatting programs, etc., out there for such use.  this
> would only get you the IBM 250K MFM format, but that's supposed to be
> supported on the 8280, so I _think_ one would do OPEN
> 15,8,15,"N0:MYDISK" to not format the media, but write out a BAM and
> directory track).  A valid but admittedly intermediate test to
> formatting the whole thing.
If I don't make progress in the immediate future, that could be a plan.

> Oh... and since it's a dual drive, I'd also consider OPEN
> 15,8,15,"N1:MYDISK,XX" and if that failed the same way, I would
> probably proceed under the expectation that both drive mechs are
> probably not faulty in the same way.
Yep, I swapped the mechanisms, both exhibit same behaviour. This is why
I initially thought the DOS board but now wonder if it's the media.

> Sounds like you have someone to send you an 8280 disk so you may be
> all set, but I'd be impatient enough to at least fiddle with something
> to read blocks on different tracks just to ensure the FD1797 FDC is at
> least nominally happy.  Of course that won't test read/write and data
> sep circuits or the TM848 heads, but it would test everything up to
> that point.
And I am indeed an impatient person so will continue fiddling. I have a
couple of spare controller IC's, and all show same behaviour, so at
least that can be ruled out.

cheers, Rob

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Re: Need an 8280 formatted 8" disk

Rob Clarke
In reply to this post by Mike Stein
Ahh, now - the disks I have only has a single index hole - maybe this is
the issue? Maybe there was some extra setting to format single sided?


On 13/02/2017 18:43, Mike Stein wrote:

> Hi Rob,
>
> Can't help you with a formatted disk but if you have trouble finding blanks once you get things sorted, let me know.
>
> Note that single and double-sided disks have the index hole in different locations; most double-sided drives including the TM-848 have two sensors and can use both types, but it's something to keep in mind just in case.
>
> m
>
> ----- Original Message -----
> From: "Rob Clarke" <[hidden email]>
> To: <[hidden email]>
> Sent: Monday, February 13, 2017 7:54 AM
> Subject: Need an 8280 formatted 8" disk
>
>
>> Gents,
>>
>> I'm desperately in need of a known good 8" floppy formatted on an 8280.
>> After 18 months of occasional work, I now have my 8280 up and running,
>> or at least I think I do. DOS board is up and running, the drives are
>> refurbished and behaving, and I have a good power source. I can trace
>> signals all the way from the FDC to the read/write heads and back again.
>>
>> Nevertheless, using the 2 no-name 8" disks I have, the format fails with
>> an error 21 on track 0, sector 1 every time. So, to track the fault down
>> it would really help to have a good disk. Either I can post one of my
>> disks to someone or, if you hace a spare 8" disk, I'd gladly compensate
>> for that and time, postage etc...
>>
>> Regards, Rob
>>
>>
>>        Message was sent through the cbm-hackers mailing list
>         Message was sent through the cbm-hackers mailing list


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Re: Need an 8280 formatted 8" disk

Francesco Messineo
In reply to this post by Rob Clarke
Hi,
just a suggestion: you could adapt a 5.25" HD drive in place of the 8"
just to test the controller, afair they have the same revolution speed
and data rate.
That said, I have a couple of boxes of 8" floppies but with unknown
(to me) format and media state since I don't have any 8" drive (I
whish I had).
I could donate a floppy anyway.
Frank

On Mon, Feb 13, 2017 at 7:03 PM, Rob Clarke <[hidden email]> wrote:

>
>> I wasn't suggesting going to that point, rather a simple BASIC program
>> to do a "B-R" command for blocks on different tracks which _should_
>> cause the drive to seek, then fail as the media under the head lacked
>> the correct format to produce meaningful results.  So it _would_
>> "fail", but the head would at least move around.
>
> Good plan, I didn't think of that. I just tried it with B-R and the appears
> to step up and down correctly, but of course also fails with a read error.
>
>> I looked into
>> ftp://www.zimmers.net/pub/cbm/schematics/drives/old/8280/index.html
>>   It _is_ a Tandon TM-848.  That is an easy one to hook up to a
>> "modern" machine, and for reads, you wouldn't need a "TG43" signal
>> generator (though this, from John Wilson, would take care of
>> everything including 50 pin<->34 pin wiring
>> http://www.dbit.com/fdadap.html)  If you did pull one of the drives
>> from the 8280, it could be hooked up to a PC and used as an 8" drive -
>> there are formatting programs, etc., out there for such use.  this
>> would only get you the IBM 250K MFM format, but that's supposed to be
>> supported on the 8280, so I _think_ one would do OPEN
>> 15,8,15,"N0:MYDISK" to not format the media, but write out a BAM and
>> directory track).  A valid but admittedly intermediate test to
>> formatting the whole thing.
>
> If I don't make progress in the immediate future, that could be a plan.
>
>> Oh... and since it's a dual drive, I'd also consider OPEN
>> 15,8,15,"N1:MYDISK,XX" and if that failed the same way, I would
>> probably proceed under the expectation that both drive mechs are
>> probably not faulty in the same way.
>
> Yep, I swapped the mechanisms, both exhibit same behaviour. This is why I
> initially thought the DOS board but now wonder if it's the media.
>
>> Sounds like you have someone to send you an 8280 disk so you may be
>> all set, but I'd be impatient enough to at least fiddle with something
>> to read blocks on different tracks just to ensure the FD1797 FDC is at
>> least nominally happy.  Of course that won't test read/write and data
>> sep circuits or the TM848 heads, but it would test everything up to
>> that point.
>
> And I am indeed an impatient person so will continue fiddling. I have a
> couple of spare controller IC's, and all show same behaviour, so at least
> that can be ruled out.
>
> cheers, Rob
>
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