CHAPTER 8 CD-ROM AND CD WRITER DRIVES

	Introduction :
	The data stored on the CD can last for many years. The CD can store large amounts of data and is used to distribute software, music, and movies. The CD drive reads the data stored on the CD. The CD-ROM drive can only read data from a CD. Today CD-R and CD-RW drives are available that can read, and also burn data on a CD.
8.1 Types of CDs
	Compact Disc (CD) is a removable storage media. The CD is a cheap and reliable media. The CD is a round disc with a hole in the center that stores data
	CD-ROM Disc
	The 3.5 inch floppy disk stores about 1.44 MB of data. This enabled users to only copy files of small size on the floppy disk. The CD stores more data than the floppy disk. The CD holds about 650 - 700 MB of data. The CD is made out of a clear piece of polycarbonate plastic. The CD has different layers that enable the CD drive to read data from the CD. The layers that make up the CD depend on the type, and the number of times that you can write data on the CD. The basic layers for the CD are : _ Polycarbonate plastic - Hard transparent plastic layer of the disc _ Aluminum - Reflects the laser beam from the CD drive like a mirror that reflects light _ Acrylic - Protects the CD layers _ Label - Enables you to name the CD for identification
	8.1.1 Audio Compact Disc
	The Audio CD is used to store music and has replaced the audio cassette. Regular use of the audio cassette reduces the song quality due the friction between the tape player head and the audio 174 cassette. The song quality on an Audio CD does not decrease like the audio cassette, because there is no friction between the CD player and the Audio CD. Therefore, the songs recorded on the Audio CD are of better quality and have a longer shelf life. An Audio CD can store about 74 minutes of music.
	8.1.2 CD Read-Only Memory (CD-ROM)
	The CD-ROM is used to store data for distributing software and other large files such as databases and word processors. The CD-ROM disc can also hold music and movie files. Files on a CD-ROM can only be read as the CD-ROM is stamped. In stamping, the data the CD data is written on a glass disc. This glass disc is used like a rubber stamp and is pressed on the CD-ROM and creates a permanent image of the data on the Polycarbonate plastic layer of the CD-ROM.
	8.1.3 Compact Disc-Recordable (CD-R)
	The CD-R disc is like a blank book that you can write in using a pen. The text once written cannot be erased. The CD-R is useful to backup data. The CD-R can also be used to create music CDs that can be played on music systems. The CD-R disc has a special layer between the polycarbonate plastic layer and the reflective aluminum layer to store the data on the CD-R disc. This layer is made up of a photosynthetic dye that is sensitive to strong light. When the dye is heated using a strong laser beam the dye darkens and becomes opaque. The area that is opaque does not reflect the laser beam back to the optical sensor, and is interpreted as the binary digit 0. The area on the disc that is not opaque reflects back the laser beam on the optical sensor and is interpreted as the binary digit 1.
	8.1.4 CD-ReWritable (CD-RW)
	You can write text in a book using a pencil. When you do not need the text, you can erase it from the book. The CD-RW disc enables you to rewrite data to the CD-RW disc. The data when not required can be erased from the CD-RW disc. Erasing the data from the CD-RW disc removes all the data from the CD-RW disc and makes the CD-RW disc empty for writing data to it. The CD-RW disc is useful for transferring data from one system to another, or for storing files that are updated regularly. The CD-RW has a special layer called, the phase change compound layer, that makes it possible to rewrite data to the CD-RW disc. The phase change compound is a special substance made up of silver, antimony, tellurium and indium. This substance is transparent in the solid state. When this substance is heated using a laser beam of high intensity, the substance melts to the liquid state and acts like a pit and does not allow the laser beam passing through it. Erasing the disc converts the phase change compound from the liquid back to the solid state.
8.2 Types of CD Drives
	The CD drive can be classified as the CD-ROM drive, the CD-R drive and the CD-RW drive. The CD-ROM drive reads data from a CD. The CD-R drive can read data from a CD and can also write data to a CD-R disc. The CD-RW drive can read, write and also rewrite data. _ The speed of the CD drive is specified using a number followed by the alphabet X.
	8.2.1 CD-ROM Drive
	The CD-ROM drive can read data from the CD-ROM disc and the Audio CD. You can use this drive to install software from a CD and play music from an Audio CD
	CD-ROM Drive
	The speed of the CD drive specifies the amount of data the CD drive reads from the CD in a second. This speed is called the transfer speed of the CD drive. The original speed of the CD drive is 150 KB per second. The speed of the CD drive is specified using a number followed by X. For example, if the speed of the CD drive is specified as 52X, then the CD drives reads data from the CD at a speed of 52X. The number specifying the speed of the CD drive must be multiplied with the original speed of 150 KB per second, to get the speed of the CD drive. For example if the speed of the CD drive is specified as 12X, then the transfer speed is 12 x 150 = 1,800 kbps.
	8.2.2 CD-R Drive
	The CD-R drive can read data from the CD-ROM, Audio CD, and the CD-R disc. The CD-R drive can also write data to the CD-R disc. This drive is useful for backing up data that must not be modified, on a CD-R disc. The CD-R drive can write to the CD-R disk in a single session or using multiple sessions. In the single session, the data is written to the CD-R disc and the connection is closed such that the CDR is finalized and no data can be further added to the CD-R disc. Using multiple sessions you can continue adding data to the CD-R disc until the disc is full. The speed of the CD-R drive is specified using two numbers, each number is followed by the alphabet X. The first number specifies the speed at which the CD drive reads data from the CD. The second number specifies the speed at which the CD-R drive writes data to the CD-R disc. For example, if the speed of the CD-R drive is 52X - 12X, then the CD-R drives reads data from the CD at a speed of 52X, and writes to the CD-R disc at a speed of 12X.
	8.2.3 CD-RW Drive
	The CD-RW drive enables you to read, write and also rewrite data to the CD-RW disc. This is useful for transferring data from one system to another, especially data files that are large in size such as video files. The speed of the CD-RW drive is specified using three numbers, each number is followed by X. The first number specifies the speed at which the CD-RW drive writes data to the CD. The second number specifies the speed at which the CD-RW drive rewrites data to the CD-RW disc. The third number specifies the speed at which the CD-RW drive reads data from the CD. For example, if the speed of the CD-RW drive is 48X - 12X - 52X, then the CD-RW drives writes data to the CD-R disc at a speed of 48X, writes data to the CD-RW disc at a speed of 12X, and reads data at a speed of 52X.
8.3 Structure of the CD Drive
	The CD drive consists of different parts that enable it to read data from the disc. The CD drive is a precision device because the timing of sending the laser beam and collecting the laser beam reflected from the CD must be precise. A misalignment in the structure or working of any part of the CD drive will result in an error in reading the data from the CD.
	8.3.1 Optical Head
	The optical head of the CD-ROM drive consists of a read laser and an optical sensor. The read laser targets a laser beam on the disc. The optical sensor collects the reflected laser beam from the disc. The optical head is a very delicate and expensive part of the CD-ROM drive. It is also a high precision part of the CD drive because any deviations in the alignment of the optical head, will not allow the CD drive to read the data from the disc properly. The CD Writer has two lasers, one for reading data from the CD and one laser for writing data on the CD. The strength of the write laser is very high.
	8.3.2 Head Actuator
	The head actuator moves the optical head forwards and backwards from the center of the CD to the outer end of the disc. This allows the optical head to access all the parts of the CD. The head actuator moves the optical head, away from the center of the CD, using very small intervals to follow the minute tracks on the CD.
	8.3.3 Spindle Motor
	The spindle motor catches the CD when it is inserted in the CD drive and spins it. The circumference of the CD at its center is less than the circumference at the outer edge. This means that more data is stored on the CD near the outer side than the inner side. The optical head covers more distance at the outer track of the CD-ROM disc. To enable the CD-ROM drive to read the data from the CD-ROM disc at a constant speed, the spindle motor reduces the spinning speed as the head actuator moves from the center outward.
	8.3.4 Loading Mechanism
	The loading mechanism specifies the method to load the CD in the CD drive. The frequently used method for loading the CD in the CD drive is the tray. The CD drive has an eject button that opens and closes the CD drive tray. The CD is placed on the CD drive tray after opening it. 177 CD drives also uses the caddy system to load the CD. The CD is inserted in a device known as a caddy. The caddy is a plastic case with a metal shutter. The caddy with the CD in it is inserted in the CD drive, just as a floppy disk is inserted in a floppy disk drive.
	8.3.5 Connectors
	The connector enables you to connect the CD drive to the system motherboard. The connectors are located at the back of the CD drive.
	Connectors
	The IDE cable connects the CD drive to the motherboard. The CD drive uses the 40 pin connector. You must ensure that the marking on the IDE cable is on the same side of the power supply cable when inserting it in the CD drive. The CD-ROM drive is also equipped with output connections for sound. You can connect the cable from here to the sound card or the sound output device.
	8.3.6 Jumpers
	Jumpers are switches on the hardware that enables you to change the hardware settings. The CD drive jumpers are located at the back of the CD drive. It enables you to set the CD drive as the master, or the slave. The master specifies that the hardware is set as the primary device and can control the other devices set as slave. You can also use the jumper to set the CD-ROM drive as the master or slave as per the cable selection using the IDE cable When you install two devices on the same cable one must be set as master and the other as slave. You must set the jumpers to cable select if you use a special cable to attach the devices to the motherboard. The special cables architecture sets one device to master and the other to slave.
8.4 Working of the CD Drive
	The CD-ROM drive has a laser beam that is a powerful ray of light. To read data from the CD, the CD-ROM drive flashes this laser on the CD. The laser beam passes through the transparent plastic layer of the CD and the reflecting aluminum reflects the laser beam back to the CD-ROM drive. This reflected laser beam falls on the optical sensor of the CD-ROM drive. The CD-ROM drive reads the light patterns formed according to the structure of the CD, and interprets the data stored on the CD. The CD Writer works in the same way as the CD-ROM drive for reading data from a CD. In addition to a read laser, the CD Writer also has a more powerful laser that is used to write data to the CD. The write laser modifies the CD-R disc to burn the data on the disc.
8.5 Installing the CD Drive
	Installing the CD drive connects the system and the CD drive. You must read the documentation supplied with the CD drive and the motherboard to check if the two are compatible. You may also have to configure the CD drive after installing it using the system BIOS.
	Best practice
	1. Write the details mentioned on the CD drive label such as the model number, and the serial number, in a safe place such as a diary. 2. Read the CD drive documentation thoroughly. 3. Check if there is a vacant slot available on the front panel of the system case to install the CD drive. 4. Check the motherboard to see if you can install another IDE cable, or if you must use the IDE cable connecting the hard disk to the motherboard. 5. If you are using the hard disk IDE cable, check if it can accommodate the CD drive. Note that you have to change the IDE cable if it has only one connector with one that has multiple connectors.
	Precautions
	Wear an anti-static wristband.
	Hands on exercise
	1. Adjust the jumper as required on the CD-ROM drive.
	Adjusting the Jumper
	2. Open the system case. 3. Remove a plastic panel from the front of the system case,
	Removing the Panel
	4. Insert the CD-ROM drive in the system case.
	Inserting the Drive in the System Case
	5. Attach screws to fix the CD-ROM drive in the system case.
	Attaching Screws to the CD-ROM
	6. Connect the Audio CD cable to the CD-ROM drive, if specified in the CD-ROM documentation.
	CD Audio Cable
	7. Connect the other end of the CD Audio Cable to the motherboard or the sound card, as specified in the CD-ROM documentation.
	IDE Connecting Cable
	8. Connect the IDE cable to the motherboard.
	Connecting the IDE Cable to the Motherboard
	9. Select the required connector on the IDE cable to set the CD-ROM drive as master or slave, if the CD-ROM drive jumper is set to cable select. 10. Connect the IDE cable connector to the CD-ROM drive.
	Connecting the IDE Cable
	11. Connect the 4-pin power adapter to the CD-ROM drive.
	Connecting the Power Adapter
	12. Close the system case. 13. Start the system. 14. Press the Delete key on the keyboard when the message to load the setup appears, the BIOS Setup Main menu page appears. Note that the Main menu page also displays the keys required to browse to the different options. 15. Browse to the Standard CMOS Setup option. 16. Press Enter to display the Standard CMOS setup screen. 17. Set the CD-ROM drive as the as the primary or secondary master/slave, as installed. 18. Press Esc to display the BIOS Setup Main menu page. 19. Save and Exit the BIOS Setup.
8.6 Aligning the CD Drive
	The CD drive may display errors while reading the CD from the CD drive. You must troubleshoot and check the CD drive thoroughly for defects. If the CD and all the parts of the CD drive are not defective, it may be possible that the head of the CD drive is misaligned. The alignment of the head can change after a lot of use, or due to dust particles or mechanical problems, the laser beam can miss the track and fall on the space between the two tracks. The misaligned head will not be able to read data accurately from the CD. This will leave the drive unusable. Realigning the head changes the setting of the head actuator, and re-focuses the laser beam back on the CD track. _ You must do this with extreme caution, only after the guarantee period of the CD drive has expired, and after you have tried all the other methods for troubleshooting the CD drive.
	Hands on exercise
	12. Close the system case. To align the CD drive head. 1. Open the system. 2. Remove the CD drive. 3. Unscrew and open up the CD drive. 4. Locate the screw to align the head.
	Head Alignment Screw
	5. Use a fine marker to mark the original alignment of the screw. 6. Use a screwdriver to turn the screw about 10 degrees clockwise or anti-clockwise. 7. Reassemble the CD drive. 8. Close the system. 9. Insert a CD in the CD drive and check if the CD drive reads data from the CD. 10. Repeat the above steps if the CD drive does not read the data from the CD.
8.7 Working with CD Writer Software
	The CD Writers comes with software that enables you to work with the CD Writer. You can download the required software from the Internet, from the CD Writer company website, or from websites such as www.download.com, and www.tucows.com. Using this software, you can write data to a CD-R, or the CD-RW. The task of writing to the CD involves heating the dye on CD, therefore this process is referred to as burning. CD writing software enables you to convert the files such as music files from one format to another before burning it on the CD.
	8.7.1 Ahead Nero
	Ahead Nero is a CD writing software that enables you to burn data from the system to the CD. Using this software, you can duplicate an existing CD. Nero also enables you to create a music CD or Video CD (VCD) that plays on compatible music systems and VCD players.
	8.7.2 Clone CD
	Clone CD is enables you to create a duplicate copy of a CD. This software first copies the image from the original CD. It then burns this image on the blank CD. The capacity of the empty CD must be equal to or greater than the original CD.
	8.7.3 Adensoft Audio/Data Burner
	Adensoft Audio/Data Burner software creates data backup on the CD. You can also create music CDs that can play on music systems.
8.8 Troubleshooting the CD Drive
	Troubleshooting CD drive techniques solve the problems that arise due to the improper functioning of the CD drive. The troubleshooting techniques for the CD drive can also solve the problems for the CD Writer.
	8.8.1 Cannot Detect the CD Drive
	The system cannot read data from the CD if the CD drive is not detected. When the CD drive is not detected, the drive letter does not appear in Windows Explorer. The system also displays error message while trying to read the CD from the MS-DOS prompt. The light on the CD drive also does not glow when a CD is inserted in the CD drive. Steps to correct this problem : 1. Check that the CD drive is appropriately configured in the BIOS settings. 2. Check if the cables connecting the CD drive to the motherboard are properly connected. 3. Check the cable supplying the power to the CD drive is properly connected. 4. Unplug any new hardware installed, to check if the hardware conflicts with the CD drive. 5. Check if the CD drive is defective by testing it on a different system.
	8.8.2 CD Drive Cannot Read the CD
	When the CD drive cannot read data from the CD inserted in the CD drive the system displays an error. This can cause the CD drive to skip tracks while playing music. You may also get errors while installing software or copying data from the CD to the system. 1. Check if the CD drive light glows when you insert the CD in the drive. If the light does not glow the system may not be detecting the CD drive. 2. Wash the CD using water. Wipe the CD using a dry cloth from the center towards the outer edge.
	Cleaning a CD
	3. Insert a different CD in the CD drive and try reading data from that CD. If it reads the data from the CD then the original CD may be dirty or corrupted. 4. Clean the head of the CD drive using a head cleaning CD. The head cleaning CD has a small brush that brushes the dust off the lens of the CD. You must place the head cleaning CD with the brush side down. 5. Realign the CD head.
	8.8.3 CD Writer Cannot Write Data to the CD-R / CD-RW
	Sometimes the CD Writer cannot write to the CD-R / CD-RW disc and the software used to write the CD displays an error and terminates the burn process. 1. Check if the disc has empty space for storing more data. 2. Use a different CD-R disc as the old one must be damaged or corrupted. 3. Unclose the disc session using the CD writing software, if it is closed. 4. Check if the source disc has a lot of scratches that prevents the drive from reading the data. 5. Clean the source disc. 6. Clean the CD drive using a head cleaning CD. 7. Reduce the writing speed of the CD writing software to match the speed of the CD.
	8.8.4 Creating a Bootable CD
	The system requires some important files for the user to work with the system. These files are located on the hard disk that has the operating system loaded on it. If these files are missing or corrupted, the system cannot load the files and you will not be able to work with the system. It is a good practice to keep a bootable CD handy. A bootable CD contains important files required to start the system, when the operating system does not load the files from the hard disk. You can use software such as Nero to create a bootable CD. You may need a bootable floppy disk to create the bootable CD using Nero. _ It is recommended to create and the bootable CD on a CD-RW disk and test it, before creating a permanent copy on a CD-R disk.
	8.8.5 Changing the Boot Sequence
	The system loads important system files located on the storage device connected to the system. When multiple devices are connected to the system, the system checks for required files from the connected devices in the order specified in the BIOS setup. The system loads the required files if they are located on the first device specified. If the required files are not found on the first device the system searches the files on the next device specified. You will have to change the boot sequence for installing the operating system or for booting into the system using the bootable CD. After changing the boot sequence, you must insert the bootable CD or the operating system installer CD in the CD drive when the system starts.
	Hands on exercise
	To set the sequence of the boot devices : 1. Start the system. 2. Press the Delete key on the keyboard when the message to load the setup appears, the BIOS Setup Main menu page appears. Note that the page displays the keys required to browse to the different options. 3. Browse to the Advanced Setup option. 4. Press Enter to display the Advances Setup screen. 5. Browse to the 1st Boot Device option. 6. Select the required device such as the CDROM. 7. Press Esc to display the BIOS Setup Main menu page. 8. Save and exit the BIOS Setup.
	Summary :
	In this Chapter you learnt : _ The CD is a round disc with a hole in the center that stores data. _ The CD holds about 650 - 700 MB of data. _ The Audio CD stores music. _ The CD-ROM disc is a stamped disc that is used for distributing software and other large files such as databases and word processors. _ The CD-R disc enables you to write data to the CD-R disc. The data written cannot be erased. _ The CD-RW disc enables you to rewrite data to the CD-RW disc. Erasing the data from the CDRW disc removes all the data from the CD-RW disc. _ The original transfer speed of data, of the CD drive, is 150 KB per second. _ The CD-R drive can also write data to the CD-R disc. _ The CD-RW drive enables you to read, write and also rewrite data to the CD-RW disc. _ The optical head of the CD-ROM drive consists of a read laser and an optical sensor. _ The CD Writer has two lasers, one for reading data from the CD and one laser for writing data on the CD. _ The head actuator moves the optical head forwards and backwards from the center of the CD to the outer end of the disc. _ The spindle motor spins the CD in the CD drive. _ The CD drive loads the CD in the drive using the tray or the caddy mechanism. _ Installing the CD drive allows the system to access the CD drive. _ Aligning the head actuator of the CD drive refocuses the laser beam on the CD track. _ Ahead Nero, Clone CD, and Adensoft Audio/Data Burner enables you to burn data to the CDR and CD-RW disc.