Re: Need an 8280 formatted 8" disk

Hi Rob,

There are two versions of the TM848, the TM848-1 which is single-sided only, and the TM848-2 which is both single- and double-sided.

If your drive is the -1 single-sided version (which is what the specs on Zimmer's suggest) then you will need to use single-sided disks. The difference is in the location of the hole in the sleeve; in a SS disk it's at about 12:30, whereas on a DS disk it's closer to 1:00.

Most 8" disks only have one index hole, although there were 'universal' disks with two holes where you covered up the unused one with tape or a label.

Single-sided:
https://www.staff.ncl.ac.uk/roger.broughton/museum/floppys/201042.htm

Double-sided:
https://en.wikipedia.org/wiki/File:Floppy_disk8inch.jpg

If you're desperate and only have DS disks you can always carefully punch a second hole in the sleeve in more or less the proper SS location; no need to worry about covering up the original hole.

If it's convenient, you might want to check that the index hole lines up with the sensor in the drive or, if you can spin and select the drive, check that you're getting index pulses.

Since it can use an IBM-compatible format I'm assuming that the 8280 actually uses the index signal, unlike most of Commodore's 5 1/4 drives which did not even have a sensor.

BTW, if you're going to play with making a cable to connect an 8" drive to a PC, note that if you align the 34-pin and 50-pin cables up at  the 34/50 pin end then most of the signals actually line up, while most of the missing signals are not needed.

m


----- Original Message ----- 
From: "Rob Clarke" <crock@clarke-family.org.uk>
To: <cbm-hackers@musoftware.de>
Sent: Monday, February 13, 2017 1:04 PM
Subject: Re: Need an 8280 formatted 8" disk


> 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" <crock@clarke-family.org.uk>
>> To: <cbm-hackers@musoftware.de>
>> 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
> 
> 
>       Message was sent through the cbm-hackers mailing list

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