... But it's actually 256 bytes/sector, 18 sectors/track, 35 tracks ...
;-)
----- Original Message -----
From: Mike Stein
To: [email protected]
Sent: Monday, March 25, 2019 12:28 PM
Subject: Re: [M100] question regarding floppy disks.
Sounds similar to the original IBM 5.25" format, single-sided, 512
bytes/sector, 8 sectors/track, 40 tracks, 250Kbps.
----- Original Message -----
From: Stephen Adolph
To: [email protected]
Sent: Monday, March 25, 2019 11:54 AM
Subject: Re: [M100] question regarding floppy disks.
when attached to a CoCo, you get 160k.
On Mon, Mar 25, 2019 at 11:02 AM Kurt McCullum <[email protected]> wrote:
Yeah that does sound strange. And I agree, the drive 'should' switch
based on the hole in the disk. Does it format to 720 or 1.44 when the hole is
covered?
On Mon, Mar 25, 2019, at 7:37 AM, Stephen Adolph wrote:
Kurt, agree with everything you have said.
The odd thing is-
* using an HD disk in an DD/HD drive, and covering the hole with tape,
would seem to be BAD
---> because you are telling the drive to use the wrong current
settings for the actual disk media.
However, this is apparently the way to make my system functional.
so, strange. I would have thought it would be the opposite - let the
drive decide what current to use, matched to the "cookie".
On Mon, Mar 25, 2019 at 10:19 AM Kurt McCullum <[email protected]>
wrote:
The magnetic coercivity on HD disks is different than on regular
disks. It requires more energy to lay down the tracks. If you start with a
blank HD disk rather than a pre-formatted disk then you have a better chance.
That's because once the HD tracks are laid down, you need to erase them for
your new format. If your drive doesn't have enough energy to completely erase
the existing track, it wont work. 720k disks have a lower coercivity and
therefore work with either a 720k or 1.44mb drive. A 1.44 drive has a sensor
for the open hole and when it sees that hole, it will use a higher level of
write energy to properly work with the media. When that hole is covered, it
will use a lower level which is what the 720k media is looking for. Though I do
remember that formatting a 720k disk in a 1.44mb drive didn't always work when
going back to a 720k drive.
Not sure about the Coco drive, but my TPDD2 does not work reliably
with HD disks. I have only been able to format one properly and it had data
failure shortly after.
Kurt
On Sun, Mar 24, 2019, at 6:32 PM, Stephen Adolph wrote:
interestingly,
Yes, if I take an HD disk, and tape over the hole to make it appear
to be a DD disk, then it works.
But why?
the floppy is capable of both formats...
On Sun, Mar 24, 2019 at 7:39 PM Mike Stein <[email protected]>
wrote:
Have you tried closing the HD sense hole with a piece of tape or
similar?
----- Original Message -----
From: Stephen Adolph
To: [email protected]
Sent: Sunday, March 24, 2019 6:08 PM
Subject: Re: [M100] question regarding floppy disks.
the Coco is using it's standard controller
When issuing the DSKINI 0 command the coco tries to format for
180kB.
The combination of
(Coco, std controller, PC 1.44MB drive + a 720kB dd floppy)
works
whereas
(Coco, std controller, PC 1.44MB drive + a 1.44MBB hd floppy)
does not work
this is something I don't understand!
On Sun, Mar 24, 2019 at 5:42 PM Gregory McGill
<[email protected]> wrote:
likely the floppy controller doesn't support 80 tracks or
high density.. most of the controllers of the era are ds/sd 40 track or dsdd
40 track.. are you able to format 720k? ds/dd 80 track?
Greg
On Sun, Mar 24, 2019 at 2:38 PM Stephen Adolph
<[email protected]> wrote:
I'll start by saying this isn't an M100 or TPDD discussion,
but just looking to understand something.
I have a Tandy Coco3 with a 3.5 inch floppy drive. The
drive is a standard PC drive and it is working well.
Seems though that I cannot use 1.44 MB floppies in that
drive. They don't seem to want to format.
I really don't understand where the problem could be.
- the drive and the floppy are compatible
- the disk is known good and formats at 1.44MB in a PC
- if it can support 135 TPI, why can't it support 35 TPI?
Does anyone know what's going on?
thx
Steve
