4 Nov
2024
4 Nov
'24
2:24 p.m.
Steve,
from my experience, these "Non-descript" are often the cause for format errors.
Look for high quality disk media like
Dysan 100 5.25 MD2D
2D/2D "BASF"
MD2-DD "Maxell" or
DS,DD from "3M"
In addition, these "Non-descript" disk are most likely pre-formatted by factory,
so Degaussing is recommended or at least formatting on a 360k drive.
The D: drive is the one of the external drives that has been in use most of the time, I
guess.
So it might be just the wear, or deposits of dirt on the heads. Careful head cleaning
makes most sense here.
Thomas
On 04.11.2024 02:10, Steve Lewis via cctalk wrote:
> Non-descript 5.25 DS/DD (they don't format as 1.2M disk using a 1.2
5.25"
> drive, so I'm pretty sure they are actual 360KB disks). That said, I
> haven't really fully confirmed if it's a 1.2M drive. TEAC FD-55GFR
> 142-U, because I haven't actually come across any 1.2M formatted media.
>
> I've wondered if maybe one of the heads on the D: drive the Sharp PC-5000's
> dual disk drive might have some kind of issue (either the REad or Write
> head, not sure which) - just since it seemed more likely to end up with
> some bad sectors marked when using FORMAT.COM (whereas on other systems,
> the same disk would format fine with no bad sectors).
>
> -Steve
>
>
> On Thu, Oct 31, 2024 at 7:17 AM osi.superboard via cctalk <
> cctalk(a)classiccmp.org> wrote:
>
>> Steve,
>>
>> could you please explain, what exact disk media you are using.
>>
>>
>> On 30.10.2024 05:03, Steve Lewis via cctalk wrote:
>>> Fascinating notes!
>>>
>>> I did run into oddities when using a 360KB disks in between a 1.2M 5.25
>>> drive on the '386 and the 5.25 drive on the Sharp PC-5000. I forget my
>>> exact sequence of events, but in short the MS-DOS 2.00 FORMAT.COM on the
>>> Sharp PC-5000 would start marking a few bad sectors (sometimes just a few
>>> KB, sometimes as much as 20KB of bad sectors). And yet those same disks
>>> were formatted as just fine and no bad sectors over the '386. Or, if I
>>> used IMD and wrote full MS-DOS 2.00 image to the disk, then the disk
>> would
>>> work (and boot) fine in the Sharp PC-5000. Without nit-picking the
>>> specifics here (of whatever I did) - my lesson was there is definitely a
>>> difference between a completely uninitialized disks, versus something
>> that
>>> has been previously formatted. Which, yeah, duh - but my real lesson
>> was:
>>> you can't always FORMAT.COM your way back into a bootable disk. If
>>> something else has "touched" the boot sectors, then another system
might
>>> start flagging those as bad sectors.
>>>
>>> I'm not sure if IMD (ImageDisk) trumps all that? Meaning, whatever
crap
>> is
>>> on the disk, does IMD not care? In otherwords, is using IMD kinda-sorta
>>> like degaussing (and then applying whatever the image is)? It just
>> seemed
>>> to me that however I mangled the format on a disk, IMD was always able to
>>> get me back into a usable (and bootable) disk.
>>>
>>> I do remember (vaguely for me) in the 80s we'd get boxes of
uninitialized
>>> disks, and there were generally warnings along the lines of once it was
>>> formatted to whatever system you intended to use the disk for, it was
>>> thereafter basically committed to being used for that system. (but it
>>> seems only because, back in those days we didn't typically have the
>> benefit
>>> of something like IMD software or a Greazeweasal - and I imagine the
>>> documentation from disk vendors didn't want to get into the weeds of
>> waving
>>> magnets around your disk, especially when they already had bold warnings
>> of
>>> keeping your disk the heck away from any magnets :) )
>>>
>>>
>>>
>>> Regarding the article on SF rail replacing disk drives, to avoid
>>> "catastrophic failure".... recall a while back, ActionRetro made a
RAID
>>> out of floppy disk drives (3.5"'s). With all the firmware going
into
>> modern
>>> SSD's and M.2's, I ponder the irony of "old dumb mechanical
drives"
>>> actually being (in a way) more secure.
>>>
>>>
>>> -Steve
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> On Tue, Oct 29, 2024 at 8:35 PM Fred Cisin via cctalk <
>> cctalk(a)classiccmp.org>
>>> wrote:
>>>
>>>> On Tue, 29 Oct 2024, Chuck Guzis via cctalk wrote:
>>>>> The location of track 0 is radically different in the 96 tpi and
100
>> tpi
>>>>> conventions--there's about a 6 track offset. 100 tpi drives were
also
>>>>> spec-ed as being 77 track (like their 8" relatives).
>>>> Are the tracks offset from one side of a disk to the other?
>>>>
>>>>