Re: Need an 8280 formatted 8" disk (progress!)

From: Rob Clarke <>
Date: Wed, 15 Feb 2017 21:41:41 +0100
Message-ID: <>
Yes, as Mike N. said, you need to cover the write protect notch to write 
the disk. The 8280 needs double sided disks, as it explicitly says 
"Double sided diskettes must be used and must be formatted with the 
HEADER command before using for system operation. "at the beginning of 
section 4 on the CBM_8280_Specifications.pdf document on your site Bo.

For single sided disks the index hole is at roughly 10 degrees clockwise 
from the vertical looking at the disk with the window at 6 o'clock. For 
double sided disks, the index hole is roughly 30 degrees clockwise from 
the vertical. I tried last night to cut my own index hole using a google 
image of a double sided disk as a measurement reference, but failed. :-(

Mike S., the drives in my 8280 are TM848-2's, which are the double sided 
ones but which are *not* MPU controlled, like the 828-1E and 828-2E.

cheers, Rob

On 15/02/2017 21:01, Mike Naberezny wrote:
> On 2/15/17 11:20 AM, Bo Zimmerman wrote:
>> The disk also has a write-protect tab on the bottom-right of the 
>> disk, near
>> where the read/write exposure strip is.  Came right out of the damn 
>> box that
>> way.  Could the write-protect logic on 8" disks be opposite to 5.25"? 
>> That is,
>> write is enabled when the tab is covered, and disabled when exposed?
> Yes.  The write protect notch on 8" disks has the opposite behavior of 
> 5.25" disks.  I recently repaired a CGRS Microtech PEDISK II 8" disk 
> system for PET.  I had to work through the same issues with the index 
> hole location and write protect notch.
> Now that my PEDISK II system is working, I can provide a known good 8" 
> single sided, soft sectored, single density (FM) formatted disk with 
> 77 tracks, 26 sectors per track, and a 128 byte sector length.  Disks 
> from my system have been successfully read on another.  The filesystem 
> is not be compatible with CBM drives but the disk can be used to test 
> sector read and write.
> Regards,
> Mike

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Received on 2017-02-15 21:00:26

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