cd-r

Hello I wrote to a cd-r and later wanted to amend what I had written. I gave no thought to the cd-r restrictions. The data was on a word Document and when the disc appeared I was able to remove data and add to it. How is it that a cd-r was able to be amended? I have searched everywhere like wikipedia and cannot find a site with a concise chart describing the functions/limitations of different disc media. Any help appreciated.

at a guess peter, knowing cd-r's cannot be over written, what i think you did was load in the file edited and saved it again to the cd-r, but what it did was to just add a 2nd file to the cd-r, it never over wrote the original file.

you can keep adding files to a cd-r until all the space is used up on it or you finalize/close the session on it, meaning you've set it so no more data can be written to it no matter how much space is left unused.

some wiki links

cd-rw (write to multiply times, means you can erase/overwrite the data already in a space) :- http://en.wikipedia.org/wiki/CD-RW

cd-r (write to empty space once only):- http://en.wikipedia.org/wiki/CD-R

in your case either option 2 or 3 happened i think.

The blank disc has a pre-groove track onto which the data are written. The pre-groove track, which also contains timing information, ensures that the recorder follows the same spiral path as a conventional CD. A CD recorder writes data to a CD-R disc by pulsing its laser to heat areas of the organic dye layer. The writing process does not produce indentations (pits); instead, the heat permanently changes the optical properties of the dye, changing the reflectivity of those areas. Using a low laser power, so as not to further alter the dye, the disc is read back in the same way as a CD-ROM. However, the reflected light is modulated not by pits, but by the alternating regions of heated and unaltered dye. The change of the intensity of the reflected laser radiation is transformed into an electrical signal, from which the digital information is recovered ("decoded"). Once a section of a CD-R is written, it cannot be erased or rewritten, unlike a CD-RW. A CD-R can be recorded in multiple sessions. A CD recorder can write to a CD-R using several methods including:

1:- Disc At Once – the whole CD-R is written in one session with no gaps and the disc is "closed" meaning no more data can be added and the CD-R effectively becomes a standard read-only CD. With no gaps between the tracks the Disc At Once format is useful for "live" audio recordings.
2:- Track At Once – data are written to the CD-R one track at a time but the CD is left "open" for further recording at a later stage. It also allows data and audio to reside on the same CD-R.
3:- Packet Writing – used to record data to a CD-R in "packets", allowing extra information to be appended to a disc at a later time, or for information on the disc to be made "invisible". In this way, CD-R can emulate CD-RW; however, each time information on the disc is altered, more data has to be written to the disc. There can be compatibility issues with this format and some CD drives.

With careful examination, the written and unwritten areas can be distinguished by the naked eye. CD-Rs are written from the center outwards, so the written area appears as an inner band with slightly different shading.

Hi Terrri >what i think you did was load in the file edited and saved it again Wouldn't this be the same as burning a Word document which then can be edited? I read about how the space is being consumed in packets yet legible.; amazing technology. I have some cr-rs,dvd-rs,dvd-rws and dvd+rws. Before I use one I will read about their purpose in order to utilize it properly. You once wrote that once I use file sharing, I will wonder how I got along without it. I use it daily and am learning new things about it daily. When I have file on the desktop's screen, I copy it to a document then share it with the other pc. One time a file hopped off the desktop to the other screen. I am still wondering about that one. But, you were right and it is worth the effort. Does mapping a drive save a lot of time and worry or is it just a thing you do after a while for some other reason? Regards, Peter

to be honest peter, i've never used drive mapping or don't remember ever using it anyway. glad it's helping you anyway. all you really need to know about cd's dvd's is.. - + are different formats but that doesn't really matter so much nowadays because the cd/dvd drives/machines can usually read/write to both, it used to be the drives would only be able to use - or the + format not both.(always worth checking which format your drive/dvd player supports tho just in case) r's tracks can only be written to once, cannot be erased, when full or closed/finalized can only be read. i use them for permanent back ups of my music/films rw's can be written to and erased and re-written to lots of times, be careful tho because the more you erase/write to them the more likely it is that the data written to them will be unable to be read back and lost, i use them mostly for my linux operating systems and data that may change, i never use them as my only form of backup(then again i always have more than 1 copy of r's as backup of my permanent data too).