[Coco] Read Coco floppies in my PC

Sat Mar 31 18:10:21 EDT 2012

I remember computerland. It was a smallish computer store with decent
prices. As I'm thinking about it I seem to remember the concensus was
that the HD drives wrote with a narrower (word?) track then a DD drive
and if the head alignment was a little off on either of the drives (and
that wasn't unusual) then there would be trouble. I would like to point out
that my involvement in all of this was over 20 years ago and I don't remember
much about the problem. 

I do remember that at the time it was considered to be an issue and was to be avoided.

The Other Frank

On Sat, Mar 31, 2012 at 04:14:52PM -0400, Aaron Wolfe wrote:
> Yes, you were lucky :)
> 
> You'll notice that most of the documentation of this problem uses
> words like "mostly, usually, probably" etc.
> This is because there certainly were combinations of factors that
> could make things work, or at least work fairly often.
> 
> Unfortunately, this was not very common, certainly not something to be
> relied on.  I was working at Computerland (IBM service/sales) during
> those days.  There were so many cases of people reporting broken fdd
> due to this problem that IBM actually had us put big red stop sign
> shaped stickers on the 5.25 in drives of new systems, with some text
> about the DD/HD problem.
> 
> While there is certainly some chance that some 1.2MB fdd might writ
> some disks the some Coco can read, it is a shot in the dark.
> 
> 
> 
> On Sat, Mar 31, 2012 at 4:40 PM, Frank Pittel <fwp at deepthought.com> wrote:
> > Maybe I was just lucky? Then again it's been far to long ago for me to care.
> >
> > I do remember it was a big issue at the time and the reason I had both sizes
> > in my machine. When writing a 360K floppy for someone else i would use the right
> > sized drive.
> >
> > The Other Frank
> >
> >
> > On Sat, Mar 31, 2012 at 12:31:01AM -0400, Aaron Wolfe wrote:
> >> http://www.oldskool.org/guides/oldonnew/hardware/1.2mb_to_360k.html
> >> "Everybody knows that trying to write to a 360K disk in a 1.2MB drive
> >> usually works fine for the 1.2 MB drive, but then renders the disk
> >> mostly unusable for the 360K drive. "
> >>
> >> http://www.brutman.com/PCjr/diskette_handling.html
> >> "A high density 5.25" drive can read a low density diskette just fine,
> >> even though the drive head is narrow compared to the track.  However,
> >> if you try to write to the diskette, you will write a new track of
> >> data that is much narrower than the existing data.  This will
> >> generally make the diskette unreadable in a double density drive.."
> >>
> >> http://www.vintage-computer.com/vcforum/archive/index.php/t-12114.html
> >> "You should ALWAYS format the disk in the 360kB drive. Most of the
> >> time writing data in a 1.2MB drive leaves it unreadable in the 360kB
> >> one"
> >>
> >> http://www.retrotechnology.com/herbs_stuff/drive.html#12meg
> >> "..ever since the first high-density 1.2Mb drives and media were
> >> introduced for the IBM PC. People compain they can't read 360K
> >> diskettes formatted or written on a 1.2M drive.."
> >>
> >> http://books.google.com/books?id=kG8LcWfruOAC&pg=PT145&lpg=PT145
> >> "..once that diskette has been written or formatted in the 1.2 MB
> >> drive, it will no longer be reliably readable in a 360 KB drive."
> >>
> >> http://www.linux-tutorial.info/modules.php?name=MContent&pageid=128
> >> "Problems arise if you use a disk formatted at 360K in a 1.2Mb drive."
> >>
> >> etc..
> >>
> >>
> >>
> >>
> >> On Sat, Mar 31, 2012 at 12:11 AM, Chad H <chadbh74 at hotmail.com> wrote:
> >> > Sorry..nothing against you...but I've spent most of my adult life doing things microsoft said couldn't be done.
> >> >
> >> > I think in all fairness, whether one has problems or not with this 360k issue depends on what combination of OS + Drive model they are using to work with thr 360k media..  I've used win98 almost exclusively with good TEAC and Fujitsu drives
> >> >
> >> > Aaron Wolfe <aawolfe at gmail.com> wrote:
> >> >
> >> >>Your results are atypical.
> >> >>
> >> >>The problems between 1.2mb drives and 360k drives are very well known.
> >> >> This used to be common knowledge, but I guess its been a good long
> >> >>time since anything regarding floppy disks was well known.
> >> >>
> >> >>For instance, this microsoft article details the problem:
> >> >>
> >> >>http://support.microsoft.com/kb/79538
> >> >>
> >> >>You will find further documentation in the wikipedia article on floppy disks:
> >> >>
> >> >>http://en.wikipedia.org/wiki/Floppy_disk#5+1.E2.81.844-inch_floppy_disk
> >> >>
> >> >>The crux of the issue is that 1.2MB FDD use a narrower track than 360k
> >> >>disks by design.  The read head on a 1.2MB FDD can easily read the
> >> >>wide tracks written by a 360k drive, and it can also read the narrower
> >> >>tracks written by 1.2MB drives.  However, 360k drives cannot usually
> >> >>read the narrow tracks written by a 1.2MB drive.  This means writing
> >> >>to a 360k disk with a 1.2MB drive generally renders the disk
> >> >>unreadable by 360k drives.  This is a physical property of the write
> >> >>head and not something changeable via software.
> >> >>
> >> >>
> >> >>..
> >> >>
> >> >>On Fri, Mar 30, 2012 at 11:53 PM, Chad H <chadbh74 at hotmail.com> wrote:
> >> >>> I have 9 360k pc-xt drives, all fully tested to read/write disks formatted by 1.2 mb drives without problems....?????
> >> >>>
> >> >>> Michael Graham <mkgraham at gmx.com> wrote:
> >> >>>
> >> >>>>Just FYI, most double-density (360k) drives won't read double-density
> >> >>>>disks written on high-density (1.2M) drives.  I tried this when I first
> >> >>>>got my PCjr, and it didn't work, so I had to swap the 360k drive back
> >> >>>>and forth between my PCjr and my old desktop machine until I could
> >> >>>>source another 360k drive.  I couldn't get disks written in a 1.2M drive
> >> >>>>to read on my CoCo, either.  However, disks written with a 360k drive
> >> >>>>will read back just fine on a 1.2M drive, as long as you don't try to
> >> >>>>write to them.
> >> >>>>
> >> >>>>On 3/30/2012 8:20 PM, Bill wrote:
> >> >>>>> The drives I just got are 1.2Mb, and I have tried several times to format a
> >> >>>>> 360K disk, but for some reason it won't let me. I type in the command format
> >> >>>>> b: /f:360 (which SHOULD work), but it gives me an error message.
> >> >>>>>
> >> >>>>> Has ANYONE been successful formatting a 360K disk in XP with a  1.2Mb drive?
> >> >>>>>
> >> >>>>> Thanks
> >> >>>>>
> >> >>>>>
> >> >>>>> --
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> >> >>>>
> >> >>>>
> >> >>>>--
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> >> >>>>
> >> >>>
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> >> >>
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> >> >>
> >> >
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