- 01 July, 2002 12:57
Despite living in a world where hard disks are insanely cheap, and removable media incredibly small, the humble CD doesn't show any signs of being superseded the way it has replaced the floppy disk. Although the CD was originally a read-only medium, the development of rewritable disks has meant that the floppy disk is no longer necessary, besides the fact that its humble 1.4MB is not enough for anything but the simplest of documents anymore. Additionally, the competition in removable media has thinned, with things like ZIP, JAZ and Super Floppy disks no longer being cost-effective or as widely used as CD-ROM drives.
On the other hand, however, it is worth remembering that you can pick up an 80GB hard disk for under $300- that's equivalent to about 120 CDs. That works out to less than half a cent per megabyte, but blank CDs will still only cost you half of that and rewritables will work out about the same. Add to that the fact that a standard IDE hard disk can read and write at least 60MB per second, compared to only 5MB per second for CDs. Still, the fact remains that CDs are durable, portable, convenient, small and cheap.
Whether you are looking for a cost-effective backup solution, or you just want to share files with your friends, a CD writer is pretty much an essential ingredient of any PC these days. Whatever your reasons, there are a few key considerations to bear in mind when looking at purchasing a burner:
- CD media are very cheap
- Recording speeds of 40x let you burn CDs in under three minutes
- Compatibility with almost all computers and audio devices
- Long shelf life (theoretically up to 100 years)
- Buffer underrun protection means you can use your PC while you burn
- CDs are more durable than magnetic media such as hard disks
- May require you to stop using your PC while you burn CDs
- Rewritable disks are slower and more expensive than write-once CDs
- Slow capacity compared to DVD writers, which are becoming more affordable
How CDs workHow CDs work
All three CD disc types (CD-ROM, CD-R, CD-RW) store information in grooves that are 1.6 microns wide (a micron is one one-thousandth of a millimetre; the average human hair is about 50 microns wide). Unlike magnetic storage media, such as hard disks, which store data as polarised particles on a magnetic surface, CD-Rs and CD-RWs store data as microscopic reflective and nonreflective spots along the grooves. A drive reads the disc by shining a laser onto its surface and noting how the light reflects (or doesn't) off these spots in the grooves.
Mass-produced audio CDs and CD-ROMs are stamped by small presses that create tiny bumps (called lands) and holes (known as pits) in the grooves. Pits reflect light differently than lands along a disc's aluminium or gold surface, and the laser tells the difference by measuring the brightness of the reflection. CD-Rs and CD-RWs contain light-sensitive dyes or chemicals embedded beneath layers of protective plastic. When the high-intensity recording laser hits these light-sensitive materials, they become reflective (or not).
Drive speeds: Write/Rewrite/ReadDrive speeds: Write/Rewrite/Read
What exactly does "24x10x40" mean? These three numbers refer to the recording, rewriting and read speeds respectively. So, if a device has the specifications "24x10x40", it would record a write-once CD at 24-speed, record to rewritable CDs at 10-speed, and read CDs at 40-speed. If this doesn't mean much to you, it may help to think of these figures in terms of playing an audio CD. Playing a CD is the same thing as "reading it at 1-speed". For a standard CD that is filled to capacity, this will take 74 minutes. Therefore, reading a CD at 40-speed will take one-fortieth of that time, which is roughly two minutes.
These speeds are usually calculated as an average, so be prepared to accept a little lower performance than claimed in the specifications, particularly when it comes to read speeds. At the time of writing, 40x write burners are the fastest available, with 12x to 24x recording being pretty standard.
Media types: CD/CDR/CDRW/DVD/DVDRMedia types: CD/CDR/CDRW/DVD/DVDR
These acronyms are often used loosely, and sometimes interchangeably, for the drive and the media used by the drive. A CDR or CD-R refers to a recordable CD disk, or a CD drive that can write to blank CD disk. A CDRW or CD-RW refers to a rewritable CD disk, or a drive that supports recording to rewritable disks. All CDRW drives will write to CDR media. Not all CDR drives will write to CDRW media, although this is not so much a problem as it is virtually impossible to buy a plain CDR-only drive these days! Generally speaking, the term "CD" is used as a blanket term for both CDR and CDRW disks. Some CD media can store 700MB of data or 80 minutes of audio, although 650MB and 74 minutes is the standard.
A DVD (or DVD-ROM) drive will read all CD, CDR and CDRW disks as well as DVD disks such as those used for DVD video. While DVD almost always refers to video disks, DVD media can be used for other data, as if they were high capacity CDs. These writable DVD disks are called DVD-R. A DVDR drive is a DVD writer which will read and write to CD media as well as DVDR disks. A DVDRW is the rewritable version of DVDR. DVDs can contain up to 4.7GB of data, which is almost seven times the capacity of a CD.
Internal vs ExternalInternal vs External
In the majority of cases, you'd be looking at purchasing an internal drive. These will always be cheaper and do not require any extra desk space. Bear in mind that they will require installation, although this is a simple procedure, even if you have never delved inside your PC's casing before! Buying an internal drive also gives you the option to convert it to an external drive should the need arise- a luxury you don't get with a specialised external drive.
All this aside, there are quite a few advantages to external drives, so the extra cost might be worth it to you. Firstly, an external drive is portable. It also enables you to write CDs from any PC, so if you are printing or working on one, you can burn on another. Additionally, a removable drive will usually connect via USB or FireWire port, so it won't use up an IDE connection in your PC. This means that you won't be restricted to the four drive connections that are standard on most motherboards.
On the downside, you need extra desk space for the box, and all your PCs will need compatible connectors- be it USB, USB2, FireWire etc. If you're not sure about getting an external drive, there is always the option to buy an external case sometime down the track. This will let you use an internal writer as an external writer- and possibly free up an IDE connector, as many external units available will convert the IDE interface on the drive to FireWire or USB.
Device interfaceDevice interface
There are essentially five types of connection options for CD writers. Internal drives can be IDE, which is the same interface as regular hard disk drives, or SCSI. Unless you require SCSI for connectivity reasons, such as use with musical instruments or video equipment, it is not usually worth the extra expense.
For external burners, you have a few more options. Firstly, there is USB. Most PCs built in the last few years will be equipped with USB connectors so this is a good option for compatibility. Bear in mind, though, that the newer USB2 format is much faster although less widely implemented except in very new PCs. Be careful when buying a USB2 device that your PC will be able to use it!
Next up, there is FireWire, also known as IEEE 1394. This is a high-speed connector, much like USB2, found commonly in multimedia notebooks but less so in desktop PCs. If you use FireWire for editing video from a DV camera, then this might be a good option for you. Otherwise, you'll need to upgrade your PC with a FireWire card, which not only costs around $100, it will also use up a PCI slot in your motherboard.
Last off the ranks is the PCMCIA interface. This is the "PC Card" format used in almost every notebook ever built. This is a good option for non-FireWire equipped notebooks, but not really of great use to the desktop user. That is, of course, unless you happen to have a PCMCIA adapter for your PC.
Platform: Mac/Windows/LinuxPlatform: Mac/Windows/Linux
Mac users will probably need to restrict their research to USB, USB2 and FireWire drives, as SCSI, IDE and PCMCIA interfaces are pretty uncommon in Macintoshes. Windows and Linux users have a little more freedom when it comes to hardware interfaces supported, so the next issue to consider is software support for your drive.
Software considerationsSoftware considerations
Most drives will come bundled with software of some description. Given the huge range in burning software on the market, have a good look at what you're getting. Often, it can be worth spending a bit more on a burner that comes with a good package such as Nero (Windows) or Toast (Mac), rather than a cheaper model that comes with some unknown application that might give you grief.
Remember that there are two different ways of writing data to a CD. Firstly, there is the old fashioned way of creating a disk layout and then clicking the record button. While this is satisfactory in the majority of cases, there are times when you might like to be able to save documents onto a CD, just as you would with any other disk in your PC. To do this you need to use packet writing software such as DirectCD (Roxio) or InCD (Ahead). Packet writing software runs in the background and allows you to format CDs and use them as you would any other removable medium. If you want to be able to do this, you need a drive that supports packet writing. Also, bear in mind that this is really only effective with rewritable disks. Even though it is possible to use packet writing with a write-once CD, you may find that these will fill up quickly and may never reach their 650-700MB capacity- especially if you are overwriting the same file repeatedly.
DVD/CDRW combo drivesDVD/CDRW combo drives
For about the same price as buying a DVD drive and a CD Writer, you can buy a drive that is both. This may be worth considering if you plan to upgrade to a DVD drive in the future. Bear in mind that if you wind up with an IDE DVD reader and an IDE CD burner, your PC will only support two hard drives at the same time. This is due to the unfortunate fact that almost every motherboard ever made supports a maximum of four IDE devices, be they hard disks, ZIP drives, CD-ROMs or CD writers. So, buying a DVDR drive instead can free up room for a third hard drive. Alternatively, there is always the option to install your IDE burner into an external USB or FireWire box at some point down the track if this becomes an issue.
As DVD writers start appearing under the $1000 mark, and with prices rapidly dropping in DVD media, you may need to ask yourself whether it's worth holding out for or taking the plunge! A DVD writer will give you 4.7GB per DVDR disk rather than the mere 700MB that can be squeezed onto a CD. DVD writers will also burn regular CDs and rewritables, as well as reading video DVDs. Not a bad all-in-one solution if you can justify the expense. A blank DVD disk will cost about $10 - 15, which is a similar price per megabyte ratio to blank CDs.
|AT A GLANCE|
|Comparisons between DVD and CD standards and media|
|DVD-RW and DVD+RW||CD-RW|
|DVD-RAM||No CD format|
Buffer Underrun ProtectionBuffer Underrun Protection
For a CD writer to do its job, a constant stream of data must be provided by the system so that the laser can write an uninterrupted session to the CD. Each CD writer will have a buffer memory, usually 2 or 4MB, which will iron out any fluctuations in the data stream. If this buffer empties for any reason- usually because you are using the computer for some other task while you are recording- then a buffer underrun error occurs and the CD is corrupted. Unless, that is, you have buffer underrun protection.
Until mid-2002, buffer underruns were a common problem, resulting in many CDs being recommissioned as drink coasters. The reason all this changed is because of a new technology developed by Sanyo, dubbed "Burn proof" (Buffer Under Run proof), which allows the record laser to be paused during a burn should the buffer become empty. Other buffer underrun protection is available under names such as "PowerRec" (Plextor), "ExacLink" (OAK), "SafeBurn" (Yamaha) and "JustLink" (Ricoh). The only thing to remember is that if a drive supports buffer underrun protection, the software used must also be compatible with your drive in order to utilise this feature- this is, fortunately, pretty standard. Theoretically, with buffer underrun protection enabled, you should be able to use your PC as per normal while burning, without having to worry about wasting any CDs.
MultiRead is an attempt to introduce a standard whereby drives with the widest compatibility for CD-based media can be identified. If you buy a drive that meets the MultiRead specification, you are guaranteed that it will support all CD, CDR, and CDRW disks. The MultiRead2 specification adds DVD and DVDR disks as well.
Traditionally, the 650MB/74min limit of CD media has gone hand-in-hand with CD writers being limited by their firmware or mechanics to the same capacity. A regular CD can actually store around 690MB/77min by utilising what is called the "lead-out" area of a disk. This process is called overburning, and requires software support in addition to the drive being capable of Disk at Once (DAO) mode.
Be warned, however, that not all drives support DAO or overburning and, in some cases, overburning can damage a drive! You may also find that some drives cannot read disks that have been overburned. A 700MB CD can be extended to 734MB or 83.5 minutes. While it is not a recommended procedure, it may be a point of issue for those hell bent on pushing their systems to the absolute maximum!
This may be a small consideration for most people, but if you are interested in using mini-CDs or business card style CDs, your CD writer's drive will need a groove for 8cm disks. The capacity of a mini-CD is about 185MB or 21 minutes. Some MP3 players require mini-CDs, so bear this in mind if you intend to buy one of these. A business card size CD will hold 20 to 60MB, depending on how much of the disk has been cut off.
Double density CD (Back to contents)
In 2000, Sony introduced their double density CD format that effectively doubled the capacity of a regular CD to 1.3GB. This format is referred to as DD-R and DD-RW for the rewritable version. This format is not widely available or supported, but it may be worth considering if you are not planning to distribute the disks you burn, and you think the extra capacity is necessary.
Unless you are tempted by DVDR drives or external CDR kits, you are more than likely looking at buying an IDE CDRW drive. If you are prepared to fork out some extra cash, you may decide to go with a 40x burner, although anywhere between 12x and 24x will probably do. Remember, the difference in speed between 24x and 40x equates to less that a minute and a half in burn time.
Check that the drive you buy supports buffer underrun protection, mini-CDs, and has MultiRead compatibility. Make sure you get some good bundled software, as well as a connector cable and warranty. Also check that your PC has at least one more IDE interface on your motherboard (i.e. less than four hard drives and/or CD-ROMs already installed). Otherwise, if you're going with an external, SCSI, USB, USB2 or FireWire drive, make sure your PC supports it or can support the upgrade required (e.g. an extra PCI card slot in the motherboard). Then, if you've made it this far, you should be burning in next to no time!