CD-Rs

[manjunath]

http://www.PCGuide.com/ubb/smile.gif
Take a case where a person has kept a file on a CD - R , for working on at at different locations. If that person, has say created a data base, and later has to change data in, say record no 5.

At the first instance, the database would have been "recorded" serially on the spiral track. Later when that person has to ammend the record no 5, how is it made ?

Does the record get edited in the original place? (Doubtful)
or
Does the record get deleted in the original place and the revised record get added at the start of empty "space". If it is so, how and where would the data which informs that while reading a file, after having read record no 4, it has to go to some other place read the edited record 5 and get back to start of record no 6.
or
Does the entire file get deleted and a fresh edited file be created ? If this is so, then it is better to start a CD-R manufacturing unit. http://www.PCGuide.com/ubb/cool.gif

[This message has been edited by manjunath (edited 05-26-2002).]

[This message has been edited by manjunath (edited 05-26-2002).]

[kayofcircles]

Well, manjunath, my brain is tangled now. http://www.PCGuide.com/ubb/eek.gif I don't know the answer to your question except that you can't "amend" or change a file on a CDR disk as far as I know. You can "write over" a file on a CDRW disk, and you'll get the same "do you want to replace this file?" message that one gets with a floppy drive. If you're using the CDR disk to save work files, it seems to me that it would be better if you saved the "new" version under a new name..or dated it in the file name. That way, when you are trying to get the new version off the CD, you'll know which one is which.

Did I even understand your question properly?

[rond36]

manjunath,
As Kay pointed out you can not change data on a CD-R disk you can add files to a disk that has not been closed but once it is written it is there to stay and can not be changed. To edit the file it has to be copied to the hard drive edited there than rewritten to a different CD-R disk or the same disk if it is not closed and there is enough room to write the new file.

If you need the ability to edit files on a recorded CD you will need to use a CD-RW disk and packet writing software such as Nero In-CD or Roxio Direct CD and the SW will need to be installed on all the systems that will be working with this or any other packet written disk. If you are using Windows XP it has limited support for packet written disks built-in. With a CD-RW disk and the proper SW your CD-RW will act like a 650MB floppy drive.

If what you are asking is how does a CD-RW read and write files using packet writing SW? It works in very much the same way your HDD and FDD work with files writing packets the same way your HDD writes clusters and tracking them with a FAT (CDFS). This is why you need to format a CD-RW disk before you can write packets to it.

------------------
How to Use Fdisk and Format to Partition or Repartition a Hard Disk (http://support.microsoft.com/default.aspx?scid=kb;EN-US;q255867)
How to multi-boot Windows XP (http://www.microsoft.com/windowsxp/pro/using/howto/gettingstarted/multiboot.asp)
Microsoft Expert Zone Multi-booting made easy (http://www.microsoft.com/windowsxp/expertzone/columns/russel/september10.asp)
MSKB How to multi-boot Windows XP (http://support.microsoft.com/default.aspx?scid=kb;EN-US;q306559)

[manjunath]

Thankyou Kay and Rond36.
Yesterday (29/05/2002), I had posted some data with questions to make clear what I was looking for. It does not seem to have come up.
To make things short :

1.Could someone guide me as to where to find how would a CDFS is
maintained on a CD-R.

2.While ejecting a CD-R, the software provides with 2 or 3 options based
on the CD writer software viz.
a. Keep As Is
b. Close CD so as to read in some cd drive with a type of s/w.
c. Close CD so as to be read in any cd drive
Could any one tell under which options should one eject the CD for
optimum use of CD.

I found that if I have ejected a CD-R (CD-R) either using option A or C
after creating a file, I was able to open the file and
i. edit it and save it
or ii. delete it completely.
What are the differences in ejecting the CD using the 2 or three options. http://www.PCGuide.com/ubb/confused.gif The only difference that I could see was that if I ejected the CD using option A, I was able to read the CD only in a CD writer. And if I used option C I could read the CD in any CD drive.
One more thing I observed, was that while ejecting the CD, it gave the options only if a new file is created or an existing file edited. http://www.PCGuide.com/ubb/confused.gif

[kayofcircles]

I don't know the answer to your first question. I just learned today (thanks, mjc ) that floppies use FAT 12, but can't claim to understand filing systems at all.

I used DirectCD for a year to save files..and always chose the option to close the CDR in such a way as to make it readable in all CDRoms. (If my puter went kaput, I wanted my files back!) The Help files in DirectCD specifically said that one couldn't "delete" a file off a CDR..only thing that "deletes" is the name of the file in the directory. File is still there..but you can't access it if you have deleted the name of the file. I would have to "open" the CDR to save more work to it. Later I bought a new writer and the packet writer part (UDF file format) only works with CDRW disks...so that's what I use now. One has to format them, but do not have to "open" and "close" the CDRW..and we were pleased to discover that the CDRW was "readable" in all our CDRoms.

Which software are you using?

[satyen_69]

Hi
I am new person in this. please help me my question is

" What is CD ROM drive.What is the difference between CD ROM drive and DVD ROM drive"

[satyen_69]

Hi
I am new person in this. please help me my question is

" What is CD ROM drive.What is the difference between CD ROM drive and DVD ROM drive"

[manjunath]

Kayofcircles Thank you. I do not remember the software right now. Will post later. (today being Sunday, am at home)

Satyen, a cd rom drive will not play a DVD rom but a DVD rom drive can play a CD rom, check out at http://www.pcguide.com/ref/cd/formatDVD-c.html. use search facility here to help yourself.

you could also see http://www.crutchfield.com/infocenter/S-1WZ0LvN43Fj/home/dvd_closerlook.html

[rond36]

Originally posted by manjunath:
Thankyou Kay and Rond36.
Yesterday (29/05/2002), I had posted some data with questions to make clear what I was looking for. It does not seem to have come up.
To make things short :

1.Could someone guide me as to where to find how would a CDFS is
maintained on a CD-R.

2.While ejecting a CD-R, the software provides with 2 or 3 options based
on the CD writer software viz.
a. Keep As Is
b. Close CD so as to read in some cd drive with a type of s/w.
c. Close CD so as to be read in any cd drive
Could any one tell under which options should one eject the CD for
optimum use of CD.

I found that if I have ejected a CD-R (CD-R) either using option A or C
after creating a file, I was able to open the file and
i. edit it and save it
or ii. delete it completely.
What are the differences in ejecting the CD using the 2 or three options. http://www.PCGuide.com/ubb/confused.gif The only difference that I could see was that if I ejected the CD using option A, I was able to read the CD only in a CD writer. And if I used option C I could read the CD in any CD drive.
One more thing I observed, was that while ejecting the CD, it gave the options only if a new file is created or an existing file edited. http://www.PCGuide.com/ubb/confused.gif

There was an error in my above post
If what you are asking is how does a CD-RW read and write files using packet writing SW? It works in very much the same way your HDD and FDD work with files writing packets the same way your HDD writes clusters and tracking them with a FAT (CDFS). This is why you need to format a CD-RW disk before you can write packets to it.

It should have read
If what you are asking is how does a CD-RW read and write files using packet writing SW? It works in very much the same way your HDD and FDD work with files writing packets the same way your HDD writes clusters and tracking them with a FAT (UDF). This is why you need to format a CD-RW disk before you can write packets to it.

CD-R and CD-RW disks are not the same. If you edited or deleted a file on a writen CD you must be using a CD-RW disk because you can not edit or delete data on a CD-R disk.

What Software are you using!?? Nero burnning ROM or Roxio Easy CD Creator

What type of disk are you writing on CD-R(CD write) or CD-RW(CD rewrite)

Using a CD-R disk you can only write in CDFS file system and if the files are closed they can be read by most CD-ROM drives if the files are left open they can only be read by a CD-RW drive(option A). If the files are closed but the disk is open the files can be read by most CD-ROMs but the disk can only be written to by a CD-RW drive(option c). No matter what option you choose you can not edit, delete, or move the files that have been written to a CD-R disk

Using a CD-RW disk you can write in CDFS like a CD-R or UDF format but disks writen in UDF format can only be read and writen by a CD-RW drive using packet writing software and need to be formatted before use.



------------------
How to Use Fdisk and Format to Partition or Repartition a Hard Disk (http://support.microsoft.com/default.aspx?scid=kb;EN-US;q255867)
How to multi-boot Windows XP (http://www.microsoft.com/windowsxp/pro/using/howto/gettingstarted/multiboot.asp)
Microsoft Expert Zone Multi-booting made easy (http://www.microsoft.com/windowsxp/expertzone/columns/russel/september10.asp)
MSKB How to multi-boot Windows XP (http://support.microsoft.com/default.aspx?scid=kb;EN-US;q306559)

[manjunath]

It is a CD-R I am working on. I copied a file onto the CD-R.
Ejected the CD. Put back the CD-R and opened the the file. I deleted two lines and saved it. Ejected the CD-R. Put the CD-R back, opened the file and saw that the lines(which I deleted ) were not there. I did this out on three different CD-Rs and results were same.

Later I deleted the file. On refreshing the view, the file was not shown. For this, Kayofcircles has explained as to how this happens.

I would like to know how the edition of files take place.
The original file had occupied 50 KB of space. After edition it had taken up more than 50KB of space.

I think a fresh copy of the file(edited) is not created. I infer this,because the used space (seen under the properties of the disk), did not go up by more than 10 KB. If a fresh copy was created then the used space should have gone up by an amount close to 50KB.

[iisbob]

It is possible to edit a CD-R; however ever time you do so ( as long as you don't finalize it ) you lose some " overhead ", which is the file system markers generated by the burning program-just like your FAT table, these file system markers tell the PC where the data is on a CD.

That's why the data didn't grow another chunk the size of the data-because you didn't really erase the data, you removed the file system marker.

The problem with doing open session CD's is that everytime you write new data to it without closing it, you lose some over head for the file system marker-this is why it's recommended to burn all your data at once to a CDR-to reduce the overhead. This is also why CDRW's were constructed, to allow for multiple read/re-writes.

If you notice on a CDR/CDRW, you never get the full size in your burn-simply becasue some of it ( around 50 MB's average ) is used to set up the " FAT " for the CD, so it can be read again.

Go here, this will help to answer some of your questions and possible some others you haven't thought of yet.

CDR/RW FAQ (http://www.cdrfaq.org/)






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iisbob

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