On Wed, 09 Mar 2011 15:30:30 -0600
cctalk-request at classiccmp.org wrote:
> > On Tue, 08 Mar 2011 18:14:38 -0600
> > cctalk-request at classiccmp.org wrote:
> >
> > > From: Richard <legalize at xmission.com>
> > > Subject: Re: Who will be the last HD maker down the road?
> > > To: cctalk <cctalk at classiccmp.org>
> > > Message-ID: <E1Px1RU-000789-Ic at shell.xmission.com>
> > >
> > >
> > > In article <4D75366B.21696.2604652 at cclist.sydex.com>,
> > > "Chuck Guzis" <cclist at sydex.com> writes:
> > >
> > > > We may be using flash both for external storage and internal
> > > > storage.
> > >
> > > Flash memory is problematic for secure data. Basically, its nearly
> > > impossible to securely erase a file from flash based disks.
> >
> > I don't know how that can be true. I can understand deleting doesn't
> > work but is it true a simple dd if=/dev/zero of=/dev/sdx onto the flash
> > card doesn't fill it with zeros?
>
> You can't use dd to erase an individual file.
You don't have to and that's not the point. The point is you can make a
flash drive unrecoverable using dd.
If you want individual files to be unrecoverable, just encrypt the whole
flash device and never write anything to it in the clear. Easy to implement
and a good general solution.
> In addition, there are all the machinations that Al mentioned. The device
> pretends to be a disk, but it isn't a disk.
Doesn't matter as far as I can tell. It has to store the data you give it
somewhere, or it wouldn't be useful. Therefore you can get it to overwrite
whats already there, just not at the filesystem level.
> Message: 17
> Date: Wed, 9 Mar 2011 15:05:30 -0500
> From: Joachim Thiemann <joachim.thiemann at gmail.com>
> Subject: Re: Who will be the last HD maker down the road?
> To: "General Discussion: On-Topic and Off-Topic Posts"
> <cctalk at classiccmp.org>
> Message-ID:
> <AANLkTinuT62O+YRh=V9h3Ad9zEjGwN_W4z-kvTjSRj+B at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
>
> Writing a '0' to a location of the flash that used to be '1' MIGHT
> leave the internal analogue state at a higher level than if the bit
> previously was '0'. If you then operate the flash in abnormal
> conditions (messing with the supply voltages) you MAY be able to get
> the memory into a state where the reading thresholds are "just right"
> to get the old state.
That only gets you so much. If I copy a stream from /dev/urandom to the
card having an occasional bit recoverable isn't going to help because of
all the bits that can't be recovered. From what I have read I am alot more
confident flash can be safely erased with software than I am about a
physical drive since magnetism is harder to clean out than flash. Seems to
me the point is not relying on a filesystem delete operation but actually
filling the drive with random data. And as I said destroying flash is alot
easier than smashing a hard drive.
Hello all,
We're conspicuously in need of a Sinclair ZX-80, in good condition, for
our computer museum here in New Jersey. Normally we only accept
donations, but in this case we're willing to negotiate a trade /
purchase, depending on individual needs vs. our surplus inventory.
Please contact me OFF-LIST (thanks) if you have one to part with.
Thank you.
- Evan (evan at snarc.net)
On 3/9/2011 1:00 PM, cctalk-request at classiccmp.org wrote:
> Since the 9450 implemented the MIL-STD-1750A architecture
I occasionally wonder why 1750a wasn't more widely adopted commercially,
given a fairly open specification, relatively easy to implement, mature
tools ecosystem and built in revenue opportunity from the military.
Tangentially, I've got a complete Performance Semi P1750A chipset
including MMU. I need to build something with it, if I could ever find
enough doco to really understand it.
KJ
What was the name of that 2D barcode like print pattern that was used
in the 80s in magazines to provide machine readable source listings?
I remember these appearing in BYTE, at the very least, although I seem
to recall them appearing in other magazines as well.
The idea was that you would use a wand type scanner to read the 2D
strips of data instead of entering the program listings by hand. It
seemed to be mostly used for long BASIC source code listings, although
I think I remember seeing it on some assembly hex dumps as well.
--
"The Direct3D Graphics Pipeline" -- DirectX 9 draft available for download
<http://legalizeadulthood.wordpress.com/the-direct3d-graphics-pipeline/>
Legalize Adulthood! <http://legalizeadulthood.wordpress.com>
Hi,
I've had 2 of these for a while. Took a gander at one of them last night, and lo and behold, there was a disk in 1. Depressing the button did nothing to free the disk, so I too pliers and yanked it out. It was a thing of beauty. Unfortunately though the platter was all mangled up.
Ok. Took the thing apart and the substrate or whatever the h* measured maybe a hair over .001" using a cheap caliper (won't mention country of origin). Took apart a 3 1/2" disk and it's platter measured about .003". Became feverish and measured a video tape and it was oh .00075".
I'm aware that the oxides used differs on different media. But, and I realize there's a discrepancy in the thickness, but are the platters used in a 3 1/2" disk compatible w/the 2" standard. These things are just so friggin cute, I'd like to see them running again. I doubt anyone is manufacturing 2" disks out there.
And incidentally does anyone know what computers used the Fujitsu M2551a 5 1/4" floppy drive? Something tells me it may have been used in the AT & T 6300/Olivetti?/Xerox? units, but I'm not sure.
http://www.nsrl.nist.gov/Project_Overview.htm
for an example of a large (about 18 million unique sums) database of file hashes
It is interesting that they don't claim that they are all valid files, just that they have a hash and a file/path name from a known source
