I am looking for SD (Secure Digital) memory that can be programmed only
once. Basically, once programmed, it cannot be erased. I searched the web,
but I did not find any. Please let me know if you are aware of such
technology. Thanks.

T.I.

On Jan 30, 5:20 pm, "Talal Itani" <tit...@verizon.net> wrote:
There is no such thing.

Mass-produced removable memories like this tend to use mask ROM. If
they resemble SD it's only cosmetically. Such devices have a vested
interest in NOT using a simple-to-duplicate storage format where blank
media are available off the shelf.

larwe wrote:
There are such things as OTP devices; we call them PROMs

Cheers

PeteS

On Tue, 30 Jan 2007 14:23:19 -0800, larwe wrote:

Multimedia cards have a permanent write flag in the CSD register. I
have not tried this feature but from a data sheet I have, it permanently
disables erases + writes. Not sure if SD card has the same functionality -
I don't have a technical spec for one of those.

Regards,

Paul.

PeteS wrote:
Used to be lots of them. They contained fusible links which, once
blown, can't be unblown.

--
<http://www.cs.auckland.ac.nz/~pgut001/pubs/vista_cost.txt>

"A man who is right every time is not likely to do very much."
-- Francis Crick, co-discover of DNA
"There is nothing more amazing than stupidity in action."
-- Thomas Matthews

"larwe" <zwsdotcom@gmail.com> wrote in message
news:1170195799.076196.75400@v33g2000cwv.googlegro ups.com...

The CSD register of the SD interface contains a write-once bit called
PERM_WRITE_PROTECT that does the follow (quoting)
"Permanently protects the entire card content against overwriting or erasing
(all write and erase
commands for this card are permanently disabled). The default value is 0,
i.e. not permanently write
protected."

Peter

On Jan 31, 10:40 am, "Peter Dickerson"
<firstname.lastn...@REMOVE.tesco.net> wrote:


The OP appears to be making something like those sewing machines or
fitness trainers that use removable media cards to store software
packs (stitch patterns, exercise programs, etc). SD is really not the
right choice for an application like this; even though many such
devices LOOK like SD cards, they almost never are.

The write-protect bit to which you refer can be subverted by various
means.

CBFalconer wrote:
But they can be erased, by blowing the remaining links, leaving
an unusable part with no data - perhaps not what the OP wanted.

Talal Itani wrote:
Can you explian what you are trying to use this for, and how secure,
and how large, the OTP aspect needs to be.

Is it to prevent accidental corruption, or does this hold unique IDs
that must remain secure, or is it a high revenue/high volume product
you want to protect from rampant cloning (or virus/tampering) ?

-jg

Hi Jim,

I am trying to keep people from accidentally erasing the contents of the
microSD. Basically, once it is programmed, I want the data to remain there,
and not erased or programmed again. This is for a product, yet not a mass
produced product. The size I need is 512MB. The microSD will not hold
unique ids. Thanks.

T.I.


"Jim Granville" <no.spam@designtools.maps.co.nz> wrote in message
news:45c0e647@clear.net.nz...

Thank you very much. This is exactly what I am looking for.

Clifford Heath wrote:
So what? One can ALWAYS erase the remaining bits, leaving an unusable
part. Sometimes the eraser is a hammer or torch.


--
Thad

Thad Smith wrote:
Yes, but then it's not still electrically ok. The OP said "cannot
be erased"... ok I was being facetious, you don't have to make a
fuss :-).

On Wed, 31 Jan 2007 15:40:15 +0000, Peter Dickerson wrote:
Is that an actual SD data sheet, and not a MMC data sheet? If it's an SD
data sheet, how did you get it - did you pay for it or find it on the
internet? If you got it off the internet, a link would be appreciated.

Regards,

Paul.

Hi Peter,

Thank you for this information. To write the microSD cards I have been
using USB card readers, under Microsoft XP. That setup does not give me
access to the bit you are referring to. I'm I missing something? Do you
know of tools that allow me to manipulate the bits of the CSD register? If
I write my own software under XP, will I have access to that register? I
hesitated to trouble you again, but you gave me a clear answer to my initial
question. Thanks a bunch.

T.I.

"Talal Itani" <titani@verizon.net> wrote in message
news:IQowh.4879$lk3.2184@trnddc04...
You need to use CM27 (PROGRAM_CSD). Presumably you can control the hardware
under XP with a device driver, but it will be a big job for a small task,
and hardware dependent. Whay don't you get the target hardware to do it?

Peter

Talal Itani wrote: (** top-posting fixed **)
Please don't top-post. I fixed this one. Your answer should
follow (or be intermixed with) the material you quote, after
snipping anything not relevant to your reply. Please read the
following links.

--
Some informative links:
<http://www.catb.org/~esr/faqs/smart-questions.html>
<http://www.caliburn.nl/topposting.html>
<http://www.netmeister.org/news/learn2quote.html>
<http://cfaj.freeshell.org/google/> (taming google)
<http://members.fortunecity.com/nnqweb/> (newusers)

Windows XP writes and reads SD and microSD, so device drivers should be
there already, somewhere in XP, maybe I am wrong. I do not understand why
you say that I need device drivers. You asked me: "Why don't you get the
target hardware to do it?" By target hardware, do you mean the card reader
I attach to the PC through USB?

"SanDisk" now has exactly what you described:
http://www.sandisk.com/OEM/ProductCa...ROM_Cards.aspx
SanDisk® 3D-OTP SD ROM Cards (Effectiverly SD-PROM, write-once SD-card).

In article <zoydnQ5pF4ACtSHanZ2dnUVZ_sGvnZ2d@giganews.com>, "Yuri" <yuri@levdik.org> wrote:
Regular SD cards also have two bits (bits 12 and 13 in the CSD register)
called TMP_WRITE_PROTECT and PERM_WRITE_PROTECT. There is also command 28
SET_WRITE_PROT which sets up a separate set of write protection groups.

I can't say for sure if EVERY brand of SD card supports these features,
however based on the handful of cards that I tested, the write protection
features do work. Once a card is protected, a standard card reader connected
to a Windows PC can't change the contents. Unfortunately most card readers
don't recognize internal write protection the same way they recognize the
little plastic tab on the side of the card. If the plastic tab is moved
towards the "locked" position, Windows will tell you "your disk is write
protected". If you protect the card using command 28, Windows remains
oblivious to this fact and lets you copy and delete files as much as you want,
when in fact you're not actually changing anything on the card.

Perhaps there are card readers that handle this properly, but the one that's
sitting on my desk right now (using a Genesys GL816E chip) does not. I imagine
you will run into the same problem with the Sandisk SD-ROM card.