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Install win7 on usb/flash


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#51 MedEvil

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Posted 23 November 2011 - 07:06 PM

Ok, so i did remember things a bit correct. ;)
What is actually read, are the beginning and end of the pits, just what it exactly means, was a bit scrambled up in my head. ;)

Though there is one part of the description, that seems wrong to me.
"On the land are many "pits" written in a spiral-shaped track."
I could have sworn, that the pits are arranged in rings, just like on a Floppy or HDD and not like in a record.

:cheers:

#52 Wonko the Sane

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Posted 23 November 2011 - 07:12 PM

I could have sworn, that the pits are arranged in rings, just like on a Floppy or HDD and not like in a record.


No, no, they are in a spiral allright.
http://www.lightbyte...piralLength.htm

And a same piece of data can seemingly occupy different lengths of the spiral:
http://www.laesiewor...Storage_CD.html

* Since the channel bit rate is held constant (4321800 channel bit/sec = 75 blocks/sec * 98 frames/block * 588 channel bits/frame.), then the density of the bits must vary with recording velocity. In other words, those 4321800 channel bits that encode 1 second of audio could be stored in as little as 1.2 linear meters or as much as 1.4 linear meters.


:cheers:
Wonko

#53 cdob

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Posted 23 November 2011 - 07:12 PM

it was never a question if the first 16 or 17 sectors are part of the ISO image, just if they are part of the CD, which can be reached from the file catalog.

ISO9660 9.1.3 Location of Extent uses a absolute pointer to whole media.
Yes, first sectors are available by file catalog.

Contrary Ecma 119 6.2.1

The System Area shall occupy the Logical Sectors with Logical Sector Numbers 0 to 15. The System Area shall
be reserved for system use. Its content is not specified by this Standard.

A file system driver may read sectors 0 to 15 or ignore them.

One can't remove pits, but one should be able to add some.

No user software can access a CD drive directly. Only drive firmware can access a CD.
A user software may ask the drive firmware. The drive firmware does request or deny the request.
As far as I know, no drive firmware allows to add single bits to a written sector at CD-R.

That'S how UDF on CD-R works.

http://www.pctechgui...udf-file-system
Dosn't physical sectors are written once?
UDF on CD-R requires to prepare the CD-R first.
You may delete data or change data, but physically sectors are added in both cases.
Write all sectors at a UDF on CD-R once yourself. Data can't be altered anymore.

Does anybody uses UDF packet writing boot media so far?

Windows Vista and later uses mixed mode ISO9660 UDF.
OS driver can't change files at physical sector level.
You may add data at end of physical media.

#54 MedEvil

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Posted 23 November 2011 - 07:59 PM

And a same piece of data can seemingly occupy different lengths of the spiral

Yes, there used to be two differnt ways to read/write CD. Constant angular velocity 'won'. The other was constant linear velocity.

:cheers:

#55 MedEvil

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Posted 23 November 2011 - 08:32 PM

ISO9660 9.1.3 Location of Extent uses a absolute pointer to whole media.
Yes, first sectors are available by file catalog.

Ok, 1 point for Wonko! ;)

No user software can access a CD drive directly. Only drive firmware can access a CD.
A user software may ask the drive firmware. The drive firmware does request or deny the request.

Seems more and more like this general all purpose Wonko virus, will have to target a specific Amalux. :rofl:

So firmware has to be infected, to allow the virus to infect burned CDVD and while at it, it can also infect all newly created CDVD.

Dosn't physical sectors are written once?
UDF on CD-R requires to prepare the CD-R first.

Did you notice, that contradicted yourself here?
If all sectors can only be written once, how does on go about formatting a CD for UDF?
Also maybe interesting to know, a blank CD-R isn't completely 100% blank. The groove already exists on it. And that's nothing but precreated pits.

You may delete data or change data, but physically sectors are added in both cases.

Yep, i think i have explained, how UDF works further above. Maybe wasn't quite clear.

Regarding, overwriting of sectors not possible.

A quick erase is meant to be quick (duh ...) and therefore the disc's main data area is left unaffected, or at least mainly unaffected. All (or most) data remains present on the disc. What changes is the disc's structures again, on the inside rings of the media. All references to tracks and session are deleted and the media is left in a state which seems like empty media for a CD/DVD writer (in most cases ... read further).

http://www.smart-projects.net/tips.php?tips_page=9

Guess we are doing it on a regular basis. Just not with CDVD-R. ;)


:cheers:

#56 amalux

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Posted 23 November 2011 - 09:29 PM

Seems more and more like this general all purpose Wonko virus, will have to target a specific Amalux. :rofl:

Yes but now I'll be watching for him! :devil: :raygun:

:cheers:

#57 cdob

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Posted 23 November 2011 - 10:00 PM

So firmware has to be infected, to allow the virus to infect burned CDVD and while at it, it can also infect all newly created CDVD.

As for a CD-R firmware offers hardware possibilities already.
No hardware is designed to change a single bit.
Most likely you have to change hardware first and firmware next.

Did you notice, that contradicted yourself here?
If all sectors can only be written once, how does on go about formatting a CD for UDF?

Well what's formating a CD-R? A CD-R is not a hard disk.
Format is different at different media and different operating systems.
It's writing fixed pattern at CD-R. That's marker at the spiral, a laser may find this pattern later.
This fixed pattern are written once.
This reduce much user storage space.

Regarding, overwriting of sectors not possible.
http://www.smart-pro...php?tips_page=9
Guess we are doing it on a regular basis. Just not with CDVD-R.

Yes, a CD-RW can be overwritten.

Do not mix CD-R, CD-RW, DVD-R, DVD-RW, DVD+R, DVD+RW or DVD-RAM.
All are different cases.

#58 MedEvil

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Posted 23 November 2011 - 11:28 PM

As for a CD-R firmware offers hardware possibilities already.
No hardware is designed to change a single bit.
Most likely you have to change hardware first and firmware next.

cdob, i know for a fact, that you're a smart guy. Why do you play dumb now?

If i can't write a single bit. I write a whole sector, which is empty except for 1 bit.
Or did you mean, that given the way data is written to the CD, i can't change 1 bit, but have to change at least 2?


This fixed pattern are written once.
This reduce much user storage space.

But those markers can't possibly each take up a whole sector. The loss in capacity isn't big enough for that, imo.

Yes, a CD-RW can be overwritten.

Do not mix CD-R, CD-RW, DVD-R, DVD-RW, DVD+R, DVD+RW or DVD-RAM.

Yes CD-RW are different, in the way, that they can be deleted, while CD-R can not.
But you missed my point!
On a quick erased CD-RW, non empty sectors get overwritten. So if it works there, it should be possible on a CD-R as well, just that the two writes would overlay to form a new data pattern, instead of the new one replacing the old one.

:cheers:

#59 Wonko the Sane

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Posted 24 November 2011 - 09:29 AM

Yes but now I'll be watching for him! :devil: :raygun:

Remember that virii are - by design - sneaky ;):
http://reboot.pro/8092/

:cheers:
Wonko

#60 MedEvil

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Posted 24 November 2011 - 12:15 PM

Wonko the sneaky. :lol:

:cheers:

#61 amalux

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Posted 24 November 2011 - 04:20 PM

Remember that virii are - by design - sneaky ;):

Bring it on :loleverybody:


#62 cdob

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Posted 24 November 2011 - 08:11 PM

Why do you play dumb now?

Asking the next logical step: after firmware there is hardware. Can hardware solve the request?
I don't build CD burners. Manufacturer knowledge is required.

If i can't write a single bit. I write a whole sector, which is empty except for 1 bit.
Or did you mean, that given the way data is written to the CD, i can't change 1 bit, but have to change at least 2?

There are no end user data stored at hardware level.

Compare CD-ROM ECMA-130, 19.1 8-to-14 Encoding
http://www.ecma-inte...ds/Ecma-130.htm
http://en.wikipedia....teen_modulation
http://www.s-c-h-m-i...el_8/index.html

8 to 14 encoding was introduced because of hardware limitation.
It's rather difficult to add a byte as a single bits in a existing 8-to-14 encoding.

And there is error detection and correction.
You have to set 14.3 EDC field to match changed data.
Or a adjusted firmware to ignore EDF field.

CD-R Orange Book is licenced by manufacturer and can be purchased from manufacturer.
http://www.ccs.neu.e.../info/info.html
https://www.ip.phili...ew&id=21&part=2

No optical drive is designed to assign at bit level.
It's designed to access blocks of data, several sectors.
A block may shift a small space at CD location, exact location at CD dosn't matter.
Hardware does find block later, read a whole block.
And drive firmware interpret block and returns a sector.

How accurate is a end user hardware?
It's technical possible to assign exactly a written space matching at bit level?
To overwrite at bit level, you have to position at bit level first.
I doubt it's technically possible to position at bit accuracy, given a end user drive.

Are we at a therotical, technical, philsophical or theological level?

Let's compare:
Given a overwritten mechanical hard disk.
It's possible to read previous data?


But those markers can't possibly each take up a whole sector.
The loss in capacity isn't big enough for that, imo.


http://www-soft.uni-...SH/DIRECTCD.PDF

Formatted CD-RW discs have about 530 MBytes of available space; formatted CD-R discs can store up to about 620 MBytes of data.

That's about 30 Mbytes at formatted CD-R.

Did you ever user packet writing CD-R? How did colour change at underside?
Was it filled from inside to out?
Are data added at end of previous written space?

But you missed my point!
On a quick erased CD-RW, non empty sectors get overwritten. So if it works there, it should be possible on a CD-R as well, just that the two writes would overlay to form a new data pattern, instead of the new one replacing the old one.

I miss the point still.

A CD-R uses a organic layer. To change this you have to heat this (or wait some time, that's another story)
Data can be added only.

A CD-RW uses a alloy layer. To write hits you have to heat this to 500 - 700 °C.
To erase this, you have to heat this to about 200 °C.
It's possible to write and erase at bit level.
http://en.wikipedia.org/wiki/CD-RW

#63 MedEvil

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Posted 24 November 2011 - 10:26 PM

Ok, now i finally get you.
You mean, that i can't say, write bit X. Cause it will be encoded and all changed up. Did i understand you right?

Like i said before, to alter data to something useful, one needs to have original data as well as overwrite data, with which this is even possible, given the technical limitations (8-14 encoding as well as how data is stored on the CD itself)

How accurate is a end user hardware?
It's technical possible to assign exactly a written space matching at bit level?
To overwrite at bit level, you have to position at bit level first.
I doubt it's technically possible to position at bit accuracy, given a end user drive.

This a good question!
Counter question, is bit precise writing required to add a new session to a multisession CD?

On the other hand, i remember, when a buffer underrun was the dead of a CD-R.

Did you ever user packet writing CD-R? How did colour change at underside?
Was it filled from inside to out?
Are data added at end of previous written space?

Yes i did. Something like 15 years ago. The driver constantly crashed the system, even when not writing to a CD. There were also some other complications, i can't remeber now.
Long story short, i abandoned UDF. And can't really remember enough, to answer your other qestions.

A CD-R uses a organic layer. To change this you have to heat this (or wait some time, that's another story)
Data can be added only.

:confused1: My point the whole time. On a CD-R, can't data be deleted, but maybe modified, by writing over the existing data. In which case only lands can be turned into pits but not pits into lands.

So only new pits can be created and existing ones elongated. IF precise enough writing is possible!

:cheers:

#64 ambralivio

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Posted 25 November 2011 - 01:06 PM

Medevil and Cdob,

before proceeding on, with the high risk to create misunderstandings, I'd like to say that a CD-R is completely different from a CD-RW, just starting from the media material (sensitive or not to be "erased") and, maybe, also from the hardware (laser).

Besides, please take care that the packet writing tecnique is just based on the multi-session concept, so the data are always written sequentially on the "spiral", able to be re-written on a CD-RW and not on a simple CD-R.

ambralivio




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