Roll your own CD-ROM disc (part 2): hardware options.
You may wonder what features set the low-end and the high-end CD recorder's apart, and whether you really need to buy the latest first-class models for around $5,000 or whether coach class, for well under $2,000, will suffice.
Beyond the pure budgetary considerations, the decisive factor should be the application. On one end of the spectrum, you may wish to use a CD recorder simply as an archiving device, providing far superior convenience in making backups of your critical files than floppy diskettes or tapes could provide. Of course, there's a cost involved, even for die least expensive CD recorders, but you don't really want to back up hundreds of megabytes of files to floppies nor would you enjoy putting up with the sequential access of streamer tapes when you have to restore a file or two.
On the other end of the spectrum is an application wherein you want to regularly bum a dozen or so copies of databases created for highly controlled distribution within a department or for prototype testing purposes. For reasons we will see below, this sort of application may require a more powerful CD-ROM recorder.
The hardware and software premastering/mastering requirements will depend on where your applications fit within this spectrum. One thing to remember is that, when it comes to in-house recording, every disc is a master disc.
This is the most touted feature of the CD recorders. There are single-, double-, quadruple-, and sextuple-speed recorders. The single-speed recorder burns a disk in an hour or so, the sextuple takes a mere 10-12 minutes. The higher the recording speed the higher the price tag, although it is not proportionally higher. For archiving and backup applications it doesn't really matter if it takes three minutes or six minutes to make a copy of a few large files totalling, say, 60 MB. Making a few dozen copies of 500-plus MB databases in one session, on the other hand, could definitely benefit from the higher speed, although it may be cheaper to send your master to a replicator in some cases.
If you run a photo CD lab and prepare discs for customers' film rolls, recording speed is definitely important. (Don't forget that if there is much audio to be recorded, quadruple speed doesn't make sense because audio recording is at single speed.) Having already burned your fingers on quadruple-speed recording may also persuade you to use only double-speed recording mode even if 4x speed is theoretically available, thus negating the advantage of having a quadruple-speed recorder. What you also have to realize is that you will need a much more powerful computer system if you want to go for the quadruple-speed or faster recorder. You can't just connect a top-notch Yamaha 100 recorder to a system with a 33-MHz processor and any hard drive that's around the house. Data must flow continuously (at 600-680 Kb/sec depending on the recording mode) to the recorder or the recording is stopped, and you can kiss your $10 disc goodbye. You can think of it as a respirator that must pump the air continuously or the patient dies.
The most common problem is that many hard drives require a thermal recalibration (cooling) period, which serves the same purpose as bouncing the ball or adjusting your racket strings while you wipe off the sweat and catch your breath before your next serve in tennis. The problem is, however, that if the recorder does not get served when it expects, the game is called off, and there is no referee to argue with.
One of the beauties of the Corel CD Creator and the Predictor utility in Pinnacle's RCD software is the ability to test the hard disk for sustained transfer rate. Beyond avoiding the use of drives that require thermal recalibration, there is an additional way to insure continuous data flow: having a large buffer in the recorder.
A buffer is a special memory that acts as a reservoir. The buffer holds the data for the next recording cycle and gets filled up again during the recording process. (This is what you would expect your children to do before they put the jug of ice water back in the fridge after they have drunk from it.)
The larger the buffer the lesser the chances of ruining a disc. Most of the first-generation CD recorders had only a paltry 64K buffer, the Philips CDD 521 stood out with its 256K buffer, and the Sony CDW-900E excelled in not blowing discs because of its enormous 4 MB buffer. The current models feature larger buffers to start with (Philips CDD522 has 2 MB RAM, the Ricoh RS-9200CD has 1.2 MB), or they can be expanded (the Yamaha CDR100 comes with 512K but can be expanded up to 2 MB).
CD recorders are meant primarily for recording CDs. Using them as readers is not economical, just as using a sports car for moving furniture is not the best idea. Furthermore, the access time of the recorders is very slow 600-1000 msec) even compared with the cheapest CD-ROM readers with 350-500 msec access time. The only reason you might use a recorder for reading is to test the disc right after recording or to restore files from a backup disc once in a while when disaster hits and your hard disk has crashed. At those times you don't care how long it takes to restore a file, just as long as it can be restored!
Recording Modes and Formats
Recording modes are not an issue if you create a CD in one session, which is typically what happens when you put a database on CD-ROM. However, if you need to add files to the disc over time, as in archiving applications, you need multisession or incremental recording. Most recorders can do multisession, but the limitation may be that such discs can be read only on the same device or on the same brand that was used for the creation.
Incremental recording was introduced by JVC. It allows for adding new files to the disc, and once it is final and a standard CD-ROM table of contents file is created on it, it can be read on other drives.
You really have to grill the manufacturer or the dealer to get some commitments about the readability of the discs on other drives, and, as of yet, there are no guarantees. This isn't a problem if you simply want to use the disc for backup. However, if you want to distribute the discs to a few friends or associates who have different brands and models of readers, this may very well be a problem.
Recording formats refer to the capability of creating files in compliance with the various format standards. Don't overestimate the value of the long list of formats that a recorder may support. You may not be interested in recording in HFS format (unless you want to use it on die Macintosh, but why bother when the ISO 9660 standard is just as good and is used for both the Mac and the IBM). Neither are you likely to record in the longoutdated High Sierra format, in the CD-i format, or in the Sony MMCD format (for the Walkman type CD-ROM). For textual databases ISO 9660 is the only format you need. For multimedia applications CD-DA (digital audio), CD-ROM XA (sound and text interleaved), and Kodak Photo CD formatting capabilities may be important.
Software is important, Too
Some of the hardware capabilities need to be supported by the premastering/mastering software. Since you may often choose from different software options for the same drive, next month's column will cover these software options to round out the discussions about rolling your own CD-ROM.
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|Title Annotation:||CD-ROM Commentaries|
|Date:||May 1, 1995|
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