>
>Subject: Re: FW: Third round of Diskette Experiments completed (results)
> From: ard at p850ug1.demon.co.uk (Tony Duell)
> Date: Thu, 28 Sep 2006 23:39:28 +0100 (BST)
> To: cctalk at classiccmp.org
>
>[...]
>
>
>> The Diskette Experiments, Phase III
>> ----------------------------------
>>
>> The Test Disks
>> --------------
>
>[...]
>
>> Drunk Disk
>> ----------
>
>[...]
>
>
>> Conclusion: The disk is unreadable due to a
>> physical (non-bit) failure of the disk jacket
>> and internal disk mylar heavily sticking to the
>> jacket itself.
>
>My first reaction would the to open up one side of the jacket, slide out
>the disk (and keep it the right way up!), clean the surface of said disk
>and then either 'mount a naked floppy' or use a spare jacket.
>
>It would be interesting to know if the data could be recovered if you did
>that (in all 3 cases).
I've had media both soaked and dried after soaking with various sticky
beverages. I've found they cleaned up fine and read with out dificulty.
I've mounted them with out the jacket and using an old one with cleaned
and dried media.
Generally floppies do not like any abrasive damage, holes, some solvents
and of course magnetic fields. Other than that it's amazing what
will survive.
Allison
AMBRA was made by IBM if my memory isn't faulty. It's very likely that much of the firmware is similar to IBM BIOSes.
Unfortunately, I don't have any experience with IBM PC systems of the 1991 era.
Hi,
Paul posted this a day or so after the other
post and it seems the Hot & Cold Affair disk
did work again after leaving it overnight (see
below).
Regards,
Andrew B
aliensrcooluk at yahoo.co.uk
--- Paul Panks <lumberjacks76 at lycos.com> wrote:
There is an addendum added to yesterday's
posting of Phase III of the Diskette Experiments.
Here is the addendum:
A new conclusion has been reached regarding
the second disk experiment. Additionally, the
final Phase III conclusion has been modified
somewhat to showcase this change:
"The Hot and Cold Affair
-----------------------
This test called for putting ice cubes on the
front side of the disk, while simultaneously
holding the back side of the disk over a
stovetop range at Medium heat (held
approximately 3/4th of a foot from the
surface of the stovetop due to overwhelming
heat and potential hand burn considerations).
The disk was held over the surface for a
period of ten (10) minutes, while carefully
juggling the ice cubes on the 1st surface
simultaneously.
The disk was allowed to cool for a period of
20 minutes, then read. The result was a disk
that did not read, as the internal mylar floppy
could barely be moved by force from side to
side by this person.
Conclusion: The disk was unreadable due to a
physical (non-bit) failure of the disk jacket
and internal disk mylar semi-sticking to the
jacket itself. However, after waiting overnight
and trying the disk again, it read without
error. Performing a simple read/write on the
disk -- writing (then reading back) a 2 block
sequential file -- worked flawlessly. Although
heating the disk and placing icecubes atop it
is not recommended, the disk nonetheless did
recover once it was allowed to cool overnight."
The conclusion has also been modified
somewhat. Here is the change:
"Experiment Phase III Conclusions
--------------------------------
Two of the disks were a total loss, as the
experiment never progressed beyond the first
question asked ("Could a disk still be read by
the disk drive?"). The disk in the "Hot/Cold
Affair" experiment failed at first, but then
worked upon waiting 24 hours for the internal
disk mylar to cool overnight.
Disks are not impervious to permanent and
irreversible physical damage from oatmeal,
milk, water, heat ( >= 250 degrees F ), ice
cubes, shoes and golf spikes. Heating a disk
and placing ice cubes atop it will cause it to
temporarily become unreadable, although the
disk should return to working order within 24
hours. It is nonetheless strongly recommended
by this person that end users strictly avoid
such implements (as described above) when at,
near or around a floppy disk or drive."
The entirety of the Diskette Experiments can
be viewed online here:
http://www.geocities.com/dunric/diskfun.txt
Paul
>
>Subject: Re: FW: Third round of Diskette Experiments completed (results)
> From: Jules Richardson <julesrichardsonuk at yahoo.co.uk>
> Date: Fri, 29 Sep 2006 15:54:51 +0000
> To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org>
>
>Allison wrote:
>> Generally floppies do not like any abrasive damage, holes, some solvents
>> and of course magnetic fields. Other than that it's amazing what
>> will survive.
>
>.... unless it's a 3.5" floppy made in the last 6 or so years, then you just
>need to *look* at them funny and they fail :)
Actually I was talkkking about 8 and 5,25 media I was trying to recover
data from.
>Actually, typically I find the failure rate to be about 2/3 - I don't think I
>can think of a single other product that reaches the consumer with such a high
>rating.
Jules,
The last time I'd seens that failure rate I started checking the drives.
It seeems the drives had so much dust (at work) they were scraping the
media to failure. Cleaned the drives and the problem would go away
for a few months. The media was a the cheapest 3.5 available. What
would happen is once the heads built up a mixute of media and dust
it would routinely destroy disks after one use after that. Outside
of that and outright bad drives I found 3.5" to be very reliable and
somewhat more immune to some of the things that kill soft jacket disks.
In fact when AOL was sending their virus out on 3.5" floppies (pre bloat)
I'd use them and still have a few that see regular use. I figure they are
as cheap as they come!
Allison
Hi folks,
I recently got a Data General Nova 2 CPU. It is a very late built OEM
machine (Boards say ?1973 Data General but IC timestamps tell a
different story from the time around 1977/1978).
The machine came with 80kw (!!!!!) of core memory which is two an a half
time of 32kw wich is the Nova's address space. The memory is banked by
very simple MMU which bank-switches the lower 16k. If I power the unit
up I can simply use 32kw of core. That seems to work. Have not yet
worked out how the mmu is switched. Will worry about that later...
After replacing the front panel lights I can manually read and write
memory locations. And I *think* that the CPU works. At least basically.
The machine is full of made in Germany boards made by some strange
unknown OEM company.
There is a Diablo disk drive with a diablo controller. The only function
I can see at the moment is a red led on the controller which says
"ready" in sync with the ready light on the disk drive. Drive looks
good. If I try to boot the system via the built-in dma loading routine
it simply hangs in an endless loop and nothing happens.
At the moment I would be glad to hook up some kind of "standard tty" to
the machine.
Does the Nova 2 have a standard tty port built directly into the one-PCB
cpu? That would be wonderful!
If anybody can help me with tips, tricks, software, hardware, experience
or any other interesting stuff and information - please let me know!
I don't know what to do with the machine at the moment.
I think I also could need some "standard peripherals" for the machine.
Thanks a lot!
Best wishes from Bavaria (!),
Philipp :-)
Well, I have a bunch of open expansion space in my RK07 cabinet, and I
was thinking of somehow mounting the ESDI disks inside it. What sort of
products exist for mounting these disks externally, probably in a
seperate cabinet from the controller?
I think that F/W SCSI-II (FAST-10) predated Ultra (FAST-20) by a few years, anyway: F/W SCSI was available on the
SGI Onyx (in either diff or SE) which was introduced in 1993.
I'm a big fan of SCA drives + adaptors for old systems since the 50-pin drives are noticeably ancient now (most
at around 1998 or before). A SCA drive + 50-pin adaptor is much newer (and 50-pin drives of any capacity (9GB+)
have a substantial premium over SCA and 68-pin models. Some machines (Sun lunchboxes in particular) don't have
space for a SCA drive + adaptor board, though.
The latest SCSI standard (SCSI-IV I think) no longer requires drives to support 8-bit transfers and asynchronous
mode. Some of the drives I've seen still do, but be warned...
I ran across a Japanese site that seems to specialize in selling NEC PC
9801-family items. I don't know how many 9801's ever made it to the USA,
but the architecture's fairly common in the CNC machine tools world.
http://www.pc98factory.com/
Cheers,
Chuck
