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CD-R / CD-RW Tips

CD-R Capacities Autorun has stopped functioning
CD-R Diagnostic Avoid Burning Coasters
The "X" Factor Buffer Underrun
How to create a Bootable CD Precautions before recording
Precautions after recording Storing your CD
Principles of Writing / Reading Labeling your CD
Stick-on Labels Scan at the Right Resolution
Enable DMA mode What the X factor means
  Use the information below at your own risk.  See "Terms of use"

CD-R Capacities

CD-R Media hold about 74 minutes of audio, or about 650MB of data. This is the equivalent to 450 1.44 MB floppy discs. Some CD-R blanks can hold up to 80 minutes of audio, or about 700MB of data.


CD-R Diagnostic

CD-R Diagnostic is specifically designed for:
  • People with a CD recorder that occasionally have problems with recorded CD's.
  • People involved in the production of CD-ROMs.
  • People that have had problems with CD-R or CD-RW discs and have discs with inaccessible files
  • People that are curious about the construction of CD's in general
This program doesn't repair ”coasters” or exploit features of specific CD recorders for recovering CD-R's which have been incorrectly written.  It doesn't even require a CD recorder to operate - it should function very well with all CD-ROM drives which have been manufactured in the last few years.  An exception to this is packet-written CD-R and CD-RW discs which have not been finalized yet.  These discs are only readable in a CD recorder and sometimes only the recorder which wrote them.


Avoid Burning Coasters

Here are some very important tips how to configure the system to avoid burning coasters:
  • When using Win95 OSR2 or Win98 change the workstation Typical Role from: Desktop computer -> Network server

    This must be done here:

  • [START] -> Settings -> Control Panel -> System -> Performance -> File System -> Typical role of this computer

This will increase the system file-system cache settings from 32/677 paths/files to 64/2729 paths/files. This will be very helpful for burning On-The-Fly.

  • Disable the Auto insert notification for the CD-Writer & CD-ROMs).
    This is done here (read the note below):
  • [START] -> Settings -> Control Panel -> System -> Device Manager -> CDROM -> Device Name -> Settings
  • When having problems burning On-The-Fly, just use CD-Writer software, like Nero or CDRWIN, to first create a CD Image on harddisk and then to write the CD-R from the image.
  • Use a separate disk partition/harddisk to burn from as this partition can be formatted to avoid fragmentation. If there is only one partition then regularly defragment the harddisk, containing the files which are to be burned.
    Right-Click on the disk-icon and select Properties. Click the Tools tab and click Defragment Now. This can take some time to complete depending how often this has been done and how big the drive is.
NOTE: Auto insert notification must be Enabled on the CD-Writer for Direct CD to work correctly.


The "X" Factor

The length of time it takes to record (write) a disk depends on how much data or how many minutes of audio you have and the speed of your CD recorder or rewritable. If, for example, you have a full 650 Mb of data or 74 minutes of audio, at single speed it would take 74 minutes to record. A 2X recorder (recording at double speed), it would take 37 minutes to record. If you have a 4X recorder (recording at quadruple speed), it would take 18.5 minutes.


Buffer Underrun

CD writing is a real-time process which must run constantly at the selected recording speed, without interruptions. The CD recorder's buffer is constantly filled with a reserve of data waiting to be written, so that small slowdowns or interruptions in the flow of data from the computer do not interrupt writing.

A buffer underrun error means that for some reason the flow of data from source (e.g., hard disk, CD-ROM drive) to CD recorder was interrupted long enough for the CD recorder's buffer to be emptied, and writing was halted. If this occurs during an actual write operation rather than a test, your recordable disc may be ruined.

Possible Causes of Buffer Underrun:

Hard Disk

  • Extremely fragmented hard drive.

  • Not enough space in temporary directory.

  • Hard disk compression may cause buffer underruns. We do not recommend writing from a compressed hard disk or disk partition.

  • "Dumb" thermal recalibration (only on very old hard drives).

Other Hardware

  • Spindown of CD-ROM drives you're copying data or audio from.

  • Slow source devices.

  • Source devices that transfer data in bursts.

  • Incorrect recorder controller settings.

  • Inability of the devices to sync properly.

  • Overall system configuration.

  • Computer unable to allow fast enough data transfer.

  • Conflicts with old device drivers. Do not use 16-bit (real-mode) device drivers in Windows 95 or 98. REM out any old CD-ROM drives you may have in your CONFIG.SYS file. (You don't need them anyway.)

  • Setting hard drive read ahead optimization to "none" may cure buffer underruns in some cases. (Go to the Start menu | Settings | Control Panel | System
    | Performance | Advanced Settings/File System | Hard Disk and set "Read-ahead optimization" to "None.")


  • Recording across the network (a network may be too slow to maintain adequate throughput speed).

Files to Be Recorded

  • Recording many small files.

  • Damaged source files (data loss).

  • Trying to record files in use by the system or other applications.


  • Copying from a CD that is scratched, dirty, or damaged.

  • Recorder malfunction.

Checks / Prevention

  • Defragment your hard drives at least once a week.

  • Do not record across a network. Copy the desired files to your local hard drive.

  • If your source hard disk is more than five years old, make sure it does smart thermal recalibration.

  • Record at a slower speed.

  • In any operating system, always using the newest drivers from your SCSI controller card manufacturer.

  • It may be necessary to write audio at slower speeds than those you can achieve for data, since writing CD-DA audio requires streaming more bits per second to the recorder.

  • Keep the CDs, the recorder, and your source CD-ROM drive free of dust.

  • Make sure your SCSI card is FULLY ASPI-compliant.

  • Do not try to copy empty directories, zero byte files, or files that may be in use by the system at the time of recording.

  • If your data includes more than 10,000 very small files, create a disc image first, or record at a slower speed.

  • The temporary directory should always have space free at least twice the size of the largest file you are recording.

  • The entire computer, from the motherboard bus to the recorder itself, needs to be configured properly for faster recording and highest maximum sync transfer rate.

  • Change the DMA transfer rate for the SCSI card being used.

  • Try a different brand of recordable disc.

This tip brought to you by:  Adaptec


How to create a Bootable CD

  1. Create a boot DOS diskette with FORMAT A:/S, then copy the CD-ROM device driver, msCDex.exe, and xcopy.exe (see note A 2) create a simple config.sys with the line: lastdrive=z device=my_CDrom_driver.sys /d:restore Also create a simple autoexec.bat with MSCDEX.exe /d:restore /l:z (where z is the drive letter of the cd) and copy it to the boot disk.
  2. Launch Easy CD Creator.
  3. Add all of your hard drive's contents to the Data CD layout page.
  4. Select File | CD Layout Properties | Data Settings.
  5. Check "Bootable CD."
  6. Select "ISO 9660" and click on the Properties button. Select "Any MS-DOS 8+3 name."
  7. Proceed with creating the CD. You will be asked to insert a bootable diskette; insert the disk you created in steps 1 & 2.

    NOTE A:
    1. If you wish, you can add: the keyboard files you need for your country (copy the same entries you find in the C drive Config.sys and Autoexec.bat without any paths on the new diskette Config.sys and Autoexec.bat, and the requested files); you might also want to include Fdisk.exe and to clear up or modify the partition (especially useful after a virus attack).

    2. If you're using SCSI CD drivers, you will need the SCSI driver too and the line in the config.sys for the SCSI controller device driver (note that not all SCSI-controllers and motherboards can be used to boot from CD-ROM).

    This tip is brought to you by: Adaptec


Precautions before recording

  • Do not touch the recording surface while keeping dust and fingerprints off the disk.
  • To remove dust or debris use canned air.
  • To remove fingerprints, smudges or other surface contaminants, use a lint free cloth (lens cleaner) and wipe the disk from the center hub ring to the outside of the disk, using a motion perpendicular to the tracks. Never wipe in a circular motion around the disk as this will imbed the contaminants deeper into the surface.
  • Do not expose the disk to sudden changes of temperature or humidity. This may cause the disc to warp or condensation to appear on the surface.


Precautions after recording

  • Do not write on the surface of the disk using a hard tipped pen or pencil. If you must write on the surface of the disk use a water based pen that does not contain any chemical solvents. These solvents can damage the dye layer of the disk and render the disk unusable. Writing must only be done on the protective layer surface.
  • If you will be using any adhesive labels or stickers, some precautions should be taken: 1) Labels must be perfectly adhered to the disk surface. Any bubbling or creasing will imbalance the disk which can cause tracking errors or noisy spin ups. 2) Never attempt to remove an adhered label. This can damage the protective layer or the reflective layer causing permanent damage to the disk. In addition, as with writing pens, insure your labels adhesive does not contain any chemical solvents that can become absorbed into the dye layer.


Storing your CD

  • CDR's should always be stored in their original jewel cases or caddies to minimize contaminants and surface damage. Never store CDR's one on top of another, without a jewel case.
  • Always keep CDR's away from direct sunlight or extreme heat. This too could possibly cause damage to the dye layer which is sensitive to light.


Principles of Writing / Reading

To record on a CD-R, the CD-R drive employs a laser beam with the same wavelength as that used when reading a CD (780nm), yet at a much higher strength. And to guide the laser, the CD-R disc features a spiral groove molded into its surface, unlike a pressed CD. When recording, the laser focuses on the disc, generating heat to above 300º on only the affected region. This causes the organic dye (found in the recording layer) and the substrate of that small area (0.6 microns wide) to be physically altered. Not surprisingly, the optical characteristics (refractive index) of that area are also altered and this is the difference between "burned" and "not-burned" areas which is recognized by the CD-R drive.


Labeling your CD

When labeling your CD, make sure that you use a pen that is specifically for this purpose.  The non-recordable surface of the CD is very delicate and using a hard pen or pencil can damage it.


Stick-on Labels

Using a stick-on label can be a lot more trouble than it is worth.  If it is not centered on the disk perfectly and without any air bubbles, it could wobble inside the drive making the CD useless.  Also, removing a stick-on label can render a CD unreadable.  If you are still set on using a stick-on label, make sure that it is one that is designed specifically for CD applications.


Scan at the Right Resolution

Consider what you'll be using your scans for before pushing the resolution all the way up. While it's true that even low-resolution Web images will look better if you scan them at higher resolution and then decrease the resolution before putting them online, you don't need to scan everything at 600 DPI. If you need high-quality images, then by all means bump the quality up to the max. But if you don't, dropping the resolution down can save you time on the scan and disk space for the images. 


Enable DMA Mode

When writing at higher speeds, it is advised to enable DMA (Direct Memory Access) mode.  This will help to avoid buffer underruns and other possible errors.  Here's how:
  1. In Windows 95/98/Me, go to Start> Settings> Control Panel> System and click the Device Manager tab.
  2. Double-click CD-ROM and select the model for your CD-RW drive. 
  3. Click Properties and then click the Settings tab. 
  4. Look for the DMA check box under Options and click it to put a check mark in the box. 
  5. Click OK and your PC should reboot. 
  • You may also need to enable DMA mode in your BIOS settings. To learn how to do this, refer to your system's documentation. 

Note: If you're having trouble formatting CD-RW disks, disabling DMA may solve the problem.[Top]

What the X factor means

One thing to keep in mind when looking at a CD-R or CD-RW drive is what the X factor means; multiply that number by 150 kilobytes to get the maximum data transfer rate per second. For instance, 4X write speed means that the drive is capable of transferring data at 600 K/sec., given optimal system conditions. 


Autorun stopped functioning

If your Autorun feature has stopped functioning, you can try this registry fix.



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