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

From: Mike Stein <>
Date: Wed, 15 Feb 2017 16:54:40 -0500
Message-ID: <C55C6D6ECF30447BA3AE14ECC8622EB9@310e2>
----- Original Message ----- 
From: "Rob Clarke" <>
To: <>
Sent: Wednesday, February 15, 2017 3:41 PM
Subject: Re: Need an 8280 formatted 8" disk (progress!)

> ...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.

Yeah, what confused me was this spec, also on Bo's site:
Model    : 8280
Type     : Dual 8" Floppy Disk
Media    : Single Sided, Double Density
Capacity : 1024K per disk, or 2048K total
Interface: IEEE-488
Dos      : CBM DOS 3.0
Notes    : Huuuuuugggggggeeee!!!!> 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. :-(

Maybe try making it a little larger in case it's misaligned a bit? Size is not really critical as long as the index sensor can see the LED.

> 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.

That's what I assumed from looking at Andre's picture, but the specs and users manual on Bo's site are for the 848-E.

Good luck!


> 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 22:00:02

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