Karbosguide.Com Module 4C 2

KarbosGuide.com Module 4c.. 1 CD-ROM: An introduction CD-ROM Compact Read CD-ROM and CD-R Disk Read CD-ROM and DVD are optic readable media, Only contrary to hard disks, floppy disks and tapes, Memory which are magnetic . CD-ROM --''-- Read CD-ROM, CD-R The optic storage media are read with a very thin multiread and CD-E and very precisely aimed laser beam. They supplement the magnetic media. They have clear CD-R Compact Read CD-ROM and CD- advantages in the areas of data density and Disk R. Write once on special stability: Data can be packed much more densely Recordable disks named CD R in optic media than in magnetic media. And they CD-RW Compact Read CD-ROMs and CD- have much longer life span. It is presumed that Disk R. Write and re-write on magnetic media, such as a hard disk or DAT ReWritable special disks (CD-RW). (digital audio tape) can maintain their data for a maximum of five years. The magnetism simply DVD RAM Digital Reads all CD formats. fades away in time. Conversely, the life span of Versatile Reads DVD ROM. Reads optic media are counted in tens of years. Disk and writes DVD disks Random Let us take a closer look at these disks, which are Access becoming increasingly popular for all types of Memory information, education and entertainment. There are different types: Let us start by look at the CD-ROM The Compact Disk construction. To facilitate understanding, it will be easiest to compare it with other disk types, The compact disk (CD) was introduced by Philips especially the hard disk. The CD- and Sony in 1980 to replace LP records. It is a ROM is a plastic disk of 4.6" small plastic disk with a reflecting metal coating, diameter. usually aluminum. Myriads of tiny indentations are burned into this coating. These indentations It is placed in a CD-ROM drive, contain the music in millions of bits. The CD is which is like a drawer in the PC organized in tracks. Each track is assigned a cabinet: number.

When the CD-ROM disk is placed The big advantage of the CD is its high quality in the drive, it starts to spin the music reproduction and total absence of back disk. It reaches operating speed ground noise as well as a great dynamic. During in one to two seconds. Then the operation, the software in the drive can correct drive is ready to read from the disk. errors caused by such things as finger marks on the disk. All in all, CDs are excellent music storage media. Drives and operating system

The CD-ROM The drive must be assigned a drive letter. That is a task for the operating system, which must be able to recognize the CD-ROM drive. That is usually no problem in Windows The CD-ROM (Read Only Memory) came as an 95/98. However, the alphabet can be quite messy, if there extension of the CD in 1984. In principle, the are many different drives attached. media and the drives are the same. The difference is in the data storage organization. In a CD-ROM, the data are stored in sectors, which can be read Each drive must have its own letter. They are assigned on independently - like from a hard disk. a first come first-serve-basis. The CD-ROM drive usually gets the first vacant letter after other existing drives, typically D, E, or F. But the letter can be changed in The CD-ROM has become an important media in Windows . If you hit Win+Pause, the System box opens. the PC world. It can hold 650/700 MB of data, and Find your CD-ROM drives like here (The box is Danish, but it is very inexpensive to produce. Today, there are you'll find it) : three types of CD drives and DVD drives are on their way:

Drive type Name The drive can KarbosGuide.com Module 4c.. 2 While floppy and hard disks are magnetic media, the CD- ROM is an optic media. The magnetic media work in principle like an audio cassette tape player. They have a read/write head, which reads or writes magnetic impressions on the disk. The magnetic media contains myriads of microscopic magnets, which can be polarized to represent a zero or numeral one (one bit).

In the optic readable CD-ROM, the data storage consists of millions of indentations burnt into the lacquer coated, light reflecting silver surface. The burnt dents reflect less light than the shiny surface. A weak laser beam is sent to the disk through a two-way mirror and the sensor registers the difference in light reflection from the burnt and shiny areas as zeros and ones.

Tracks

Our data consist of bits, each of which is a burnt dent or a Highlight the drive and choose Properties. Then shiny spot on the CD-ROM disk. Music CDs are designed you can arrange the drive letters: much in the same manner. The bits are not splashed across the disk, but arranged in a pattern along the track. Without that organization, you could not read the data.

The platters in hard disks and floppies are organized in concentric tracks. There can be hundreds of those from center to periphery:

The CD-ROM is designed differently. It has only one track, a spiral winding its way from the center to the outer edge:

I like to reserve the letters I: and J: for CD drives.

Once the CD-ROM spins and the operating system (DOS or Windows ) has "found" the CD-ROM drive, data can be read for processing. Now the CD-ROM works like any other drive. Only, it is This 5 km long spiral track holds up to 650 MB data in Read Only Memory! about 5.5 billion dots (each is one bit).

The CD-ROM holds its own file system called ISO 9660. It is not using FAT! Data read from CD-ROM

About Optic Data Storage Data is read from the CD-ROM at a certain speed. There are two principles used reading from a CD-ROM:

The CD-ROM can be compared to a floppy drive, because the disks are removable. It can also be CLV compared with a hard drive, because of similar data storage capacity. Actually, a CD-ROM disk Constant Linear Velocity was used in the early generations can hold up to 680 MB of data. This equals the of CD-ROM drives. It implies that the data track must pass capacity of 470 floppy disks. However, the CD- under the read head at the same rate, whether in inner or ROM is neither a floppy nor a hard disk! outer parts of the track. This is accomplished by varying KarbosGuide.com Module 4c.. 3 the disk rotation speed, based on the read head's problems, and the performance vary from drive to drive position. The closer to the center of the disk the and CD-ROM to CD-ROM. faster the rotation speed to deliver the same When you see the rotation speeds, you wonder how much constant stream of data. further this technology can be advanced. The hard disk can spin at higher speeds, because it operates in a sealed box. The CD-ROM does not, and the high rotation speed CAV causes a lot of practical problems such as noise and vibrations. Constant Angular Velocity. It is not very smart to change the rotational speed of a CD-ROM all The time, as the CLV drives do. Therefore, in more Multi-beam modern and speedy drives, the CD-ROM rotates at a constant number of rounds per minute. This An interesting development in this field is the multi-beam implies that the data transfer varies; data read CD-ROM drives. Instead of one laser beam, you put up from the outer parts of the CD-ROM are read at seven of the kind (however, only six of them are used for very high bit rates. Data from the inner parts are data read). This TrueX/Multibeam technology from Zen read slower. Research gives 36X performance from a steady 6X CLV Let us look at a modern 40X CAV drive. It rotates speed rotation. constantly with a whopping 8900 RPM. This drive See www.hival.com. They produce a so-called 40X40- will deliver 6 MB per second when reading from drives with 7 (6 data + 1 error correcting) laser beams, the outer tracks. Reading from the inner tracks it which read simultaneously. That yields genuine 40X only delivers 2.6 MB per second. An average will performance with a transfer rate of up to 6MB per second, be 4.5 MB/sec. while the CD-ROM disk only rotates like a old 8X drive. Compaq also produces a drive on this basis. Problematic readings Music from the CD-ROM The CD-ROM disk has to read in random pattern. The read head must jump frequently to different The PC CD-ROM drive can play regular music CDs. That is parts of the disk. You can feel that. It causes a smart "bonus". It requires three things: pauses in the read function. That is a  You must have a sound card in your PC disadvantage of the CD-ROM media. Also the  The CD-ROM drive must match the MPC-3 multimedia faster drives can be rather noisy. standard (all modern CD-ROM drives do) Within the next years the CD-ROM and DVD drives  You must connect the CD-ROM drive to the sound card will merge into one unified drive type. with the short special cable, which comes with the drive. The CD-ROM can easily hold sound data, which can be Rotation speed and data transmission played directly through the sound card - without use of the short cable I mentioned. It only becomes necessary, when you want to play quality sound music. Certain There are different generations of CD-ROM drives. games (such as Tuneland) contain both types of sound. Here you see their data.

S/PDIF outputs CD-ROM Data transfer Revolutions per type rate minute outermost - Some CD-ROM drives feature a S/PDIF (Sony/Philips innermost track Digital InterFace) output that can deliver a purely digital signal. This gives better sound performance and opens for 1X 150 KB/sec 200 - 530 new interconnectivity (i.e. with a minidisc-recorder). 2X 300 KB/sec 400-1060 CD-R and CD-RW 4X 600 KB/sec 800 - 2,120

8X 1.2 MB/sec 1,600 - 4,240 In 1990, the CD-ROM technique was advanced to include personal burning. You could buy your own burner. 40X CAV 2.6 - 6 8,900 (constant) MB/sec A burner is also a drive 40X40 6 MB/sec 1,400 (constant) multibeam To make your own CD-ROMs, you use a drive, which can write on special CD-ROM disks. Personally I experience no big difference between These disks have a temperature sensing layer, which can the 24X, 32X, and 40X spin drives. However, their be changed by writing. You can only write on any given speedy rotation of the disk causes many physical part of these disks once. This CD-R disk is also called a WORM disk (Write Once Read KarbosGuide.com Module 4c.. 4 Many). Once the CD-R is burnt, it can be read in Steady data streaming most newer CD drive – for sound or data. Burning a CD-ROM requires a very steady data streaming. Most people use CD-Recorders for: Therefore the drives typically have a 2 MB cache onboard  Copying music CDs for personal use for buffer. If the buffer runs out of data during the writing  Backing up data (documents, images, programs) process, the CD ends up unusable.  Producing MP3 CDs (with up to 12 hours of This so-called buffer under run happens quite often, music) especially if you process other disk-intensive work on the PC while burning a CD-ROM in a EIDE-based drive. CD-RW If you use an EIDE burner, the best is to connect it as a master unit on the secondary EIDE channel with the hard The CD-ReWritable (CD-RW) is another type of disk and CD-ROM drive on the other channel. CD, where you can write multiple times on the Therefore I use this setup: same disk surface. However, not all CD drives can read these CDs. New drives, which can adjust the laser beam to match the current media and hopefully read the CD-RW disks, are called multiread. To work with CD-RW you need special software like Adaptecs. It comes with the HP 8100 drive:

It works fine, I can "burn" what I want at 12X speed. I also burn directly from CD-ROM til CD-R without copying to a harddisk. In the last case, it is best to leave the machine undisturbed during the process, even with modern "burn-proof" CD-recorders. If you need harddisk number two in a configuraton as above, you should not connect it as a slave on the vacant EIDE 2 slave channel. Instead I recommend the inexpensive FastTrack controller for expanding your EIDE system. Or better: Get yourself a 60 or 80 GB harddisk! You need to format the CD-RW disk before use: Burn speed and buffers

In 2000 the best drives selling were operating at speeds like 40x20x10x. This meens :  CD-ROM 40X  CD-R 20X  CD-RW 10X Here you see an drive called PleXWriter 12/10/32A:

It also includes a new technology With the falling prices of CD-R medias the CD-RW called "BURN-Proof". It should option has become less interesting. Most people enable the recorder to pause if the Buffer-Under-Run- do not use CD-RW very much, from what I hear, situation occurs. When data start rolling again, the they just burn the CD-Rs they need. recorder continues writing where it left. I do not know if it works (it probably does), but I do know, that this is a very The CD-R/RW good drive. It holds 2 MB of cache. The HP 9310e is another top-drive. It is rated for the speeds 32x10x4x. On EIDE interface The HP 9310e is also a very fine The best interface for CD-R and CD-RW drives is performer. It holds a buffer of 4 or used to be SCSI, but many vendors supply the MB cache, which is quite a lot. I cheaper and very reliable EIDE units. The leading use this combi-drive myself. It company HP makes great IDE-based CD-RWs. works fine: KarbosGuide.com Module 4c.. 5 DVD disks are read by a laser beam of shorter wave- Personally I do not length than used by the CD-ROM drives. This allows for understand why they do smaller indentations and increased storage capacity. not use 16 or 32 MB for buffer - RAM being so The data layer is only half as thick as in the CD-ROM. This cheep. it would opens the possibility to write data in two layers. The outer effectively remove the gold layer is semi transparent, to allow reading of the buffer under run underlying silver layer. The laser beam is set to two problem. The 4 MB of different intensities, strongest for reading the underlying buffer in HP 9310e is good for a 2,3 seconds long silver layer. Here you see a common type DVD ROM drive: delay at 10X speed burning. Personally I do not care if the recorder burns at 12x, 16X or 20x speed - it only takes few nminutes to burn a CD in any case.

Synchronize data transfer

One detail. In Windows 98/Me: Check your for Settings on both CD-ROM drives. You should enable Synchronize data transfer as here: The DVD drives come in EIDE and SCSI editions and in 5X, etc. versions, like do the CD-ROMs.

The DVD drives are often bundled with a MPEG-2 decoder. This is required if you want to replay DVD video disks at optimal quality. Some graphics cards like Matrox-G400 MAX come with a Cinemaster-based software decoder. This works together with the graphics accelerator chip and Please do not enable DMA on your CD-ROM drives. gives reasonable DVD replay quality. It probably causes troubles. The DVD drives will not replace the magnetic hard disks. The hard disks are being improved as rapidly as DVD, and Karbosguide.com Module 4c.3 they definitely offer the fastest seek time and transmission rate (currently 20-30 MB/second). No optic media can keep up with this nor with the speedy seeks we get from An introduction to the DVD the harddisks. But the DVD will undoubtedly gain a place as the successor The DVD is a high-capacity optic media. to the CD-ROM. New drives will read both CD-ROMs and The DVD standard was developed in the mid DVDs. 1990s by leading companies like Philips and Sony. DVD stands for Digital Versatile Disk. The DVD is an all-round disk, which probably will Various DVD types replace CD-ROM and laser disks. Over a few years DVD should replace VHS tapes for videos as well. Some DVD drives can both read and write the We have several versions of the DVD: disks. The drives are sold in many versions and with many incompatible sub-standards. DVD-ROM

This is the most simple format made for data read-only. It A CD-like disk is like a beefed-up CD-ROM. This medium is usable for distribution of software and other data for PC use. The DVD is a flat disk of the same size as a CD. It holds a diameter of 4.7 inches (12 cm) and is .05 The outer layers can hold 4.7 GB, the underlying 3.8 GB. inches (1.2 mm) thick. Data are stored in a small The largest version can hold a total of 17 GB. indentation in a spiral track, just like in the CD, only the tracks are more narrow. KarbosGuide.com Module 4c.. 6 A single layer DVD-5 disk holds 4.7 GB. A dual- The DVD Video Disk layred DVD-9 disk holds 8.5 GB. The dual-sided DVDs are named DVD-10 (9.4 GB) and DVD-18 The DVD video disk is the most well-known DVD format. It (17 GB). is a 4.7 GB disk, which can hold up to135 minutes top quality video with 8 digital soundtracks (AC3, Digital DVD Video disk Dolby) and sub-titles in 32 languages. Plus special features like interviews and trailers, alternate versions. This the most important standard. it is a highly sophisticated and very complex format mixing Playing of movies (with a new MPEG-2 compression) video, sound and data in a very special format. requires a transmission rate of about 600 KB per second. That corresponds to the 4X CD-ROM drives., DVD-R The Dolby AC-3 is a sound system with five full range speakers to surround you with sound, plus a The Recordable DVD are written once only like CD- supplementary low frequency special effect channel. To R. This disk can hold 3.95 GB per side . get the full use of the movie sound tracks, you need a AC- 3 compatible stereo set up. DVD RAM/+RW The DVD video disk is protected against illegal copying. There a at least three different and in-compatible formats of re-writable DVD. The disk can be MPEG-2 decoding written and read like a hard disk or perhaps more like a CD-RW. The video format on DVD disks is in MPEG-2 coding. That is a compression technology, which requires lots of DVD RAM processor power. When you buy or rent a DVD video disk, the digital video stream of the movie has been heavily Three writable technologies are present at the compressed. Hence, the data stream from the disk has to market: be decoded when you watch the film. This has to be done  Pioneer has a DVD-Recordable technology in real-time during the replay (real time decoding). placing 3.95 GB per disk.  DVD-RAM is a RW-disk from Hitachi and Soft or hard decoding? Matsushiti. The 1. generation disks hold 3.6 GB, while the 2. generation hold 4.7 GB. The disks are hold in a special cartridge. MPEG-2 decoding can be done in two ways:  The so-called DVD+RW, supported by HP, Sony,  Software based decoding Philips, Yamaha, Ricoh and Mitsubishi holds up to  Hardware based decoding 4.7 GB per disk. The software-based decoding is done by the PCs CPU using None of the three products are compatible. special software. This is not always very good since it However, the companies behind DVD+RW control drains the PC. Also the CPU seldom is powerful enogh to 75% of the market, so I think this will become the perform a perfect decoding. Some graphics chips include new standard. DVD decoding features, but have to work together with a It appears that the DVD-RAM disks are extremely software decoder as well. sensitive to greasy fingers and other . The software based decoding does not require any new contaminants. Therefore they must be handled in hardware, but it requires a very powerful CPU and/or special cassettes, which do not fit into ordinary graphics adapter. If there is not sufficient processor DVD players. power, you will see a loss of some individual images. The movie gets "choppy." The hardware-based decoding is to prefer. Here the PC is HP DVD 3100i equipped with a special chip (on an adapter) which only has to decode the MPEG data stream. The most well- HP has a DVD+RW drive. It reads and writes 3 GB known products are based on the called Real Magic disks at 1,7 MB/sec. The DVD+RW disks should be Hollywood+ chipset. readable to ordinary DVD drives. 3100i is an internal SCSI drive. It reads and writes DVD+RW media at a speed of 1.25X (1.7MB/s), which compares to 11X CD-RW write speed. The drive rotates with constant angular velocity (CAV). Using Adaptec's Direct DVD, you can drag and drop files to DVD disk from Microsoft Windows Explorer. KarbosGuide.com Module 4c.. 7 These units only play DVD video disk and do not interface with the PC.

Multiplayers

In 1999 we suddenly saw a series of new products, namely integrated CD, MP3 and DVD players from Taiwan. The devices are designed to fit into the HIFI stereo set: The advantage of the hardware based decoding is that the result does not depend on the CPU in your PC. The disadvantage is that you need to install an extra card in the PC to enable seeing DVD films. It often comes with the DVD drive as here:

I have one of those new players myself, and it works fine. It plays so to say any type of optic disc, be it music CD, CD-R with (12 hours of) MP3, DVD or small laserdiscs. The device is based on a standard PC DVD drive, so it can be pretty noisy. The Video DVD replay is comparable to the one from a PC with DVD drive and MPEG-2 adapter.

The regional codes However, MPEG cards are not always powerful enough either, according to the reviews and to DVD movies are made in several "codes." Region one is what I so far have seen. All in all, I might wait for USA and Canada, while Europe and Asia is region two: further DVD and MPEG developments. In a couple of years the MPEG decoding will surely become a standard task (included in graphics chip sets), which all PC’s can perform without problems.

The players

You can view DVD video several ways:  In a PC with a DVD drive as described above.  Using a specific DVD-player.  Using a Sony PlayStation2 device. If you use your PC to replay videos, you should have a hardware-based MPEG-2 decoder in the PC. But the best replay comes from a DVD-Video When you play movies, your hardware (MPEG decoder) home player: must match the DVD region. The movies are made in separate formats, each with their own coding. The DVD drives has to be set to one of the codes, and this setting can be changed perhaps five times.

Most players can be altered so the become code-free. The operation is quite simple, but it is a violation against the one year guarantee.

Many European users dislike the coding system: The companies sell the same movie at higher prices for region 2 than for region 1. This region thing is a typical example of industrial stupidity. From the consumers view, there is absolutely no need for this division of markets. It only makes things more difficult and expensive. KarbosGuide.com Module 4c.. 8 Incidentially Sony PlayStation2 machine are cabable of playing both region 1 and 2! This was not intended. It only goes for some region 1 DVDs, though.

A typical reaction from PC nerds and hacker types have been to crack the DVD encryption. In 1999 a 14 years old Norwegian boy was succesfull in this. The industry tried to prosecute him ...

To understand their worry, we have to look ahead. Today it is hard to imagine many copys from DVD video disks made on DWD-recorders. But maybe in 5 to 10 years we will have digital copies of all the Hitchcock movies circulating in Napster-like networks as the situation is with music and MP3s today.