Hardware Reference
In-Depth Information
Whenever a drive writes data to a disc in either DAO or TAO mode, it writes to the spiral track on
the disc, alternating on and off to etch the pattern into the raw media. Originally, it was not possible
for a drive to realign where it starts and stops writing like a hard drive can; after it started writing, it
was necessary to continue until finished with the track or disc. Otherwise, the recording (and disc if it
is not rewritable) would be ruined, creating a useless disc often referred to as a “coaster.” To avoid
this problem, the recording software, in combination with your system hardware, must be capable of
delivering a consistent stream of data to the drive while it's writing.
Sanyo was the first to develop a technology that eliminates buffer underruns once and for all. It calls
the technology BURN-Proof (BURN stands for
buffer underrun
), which sounds a little confusing
(some people thought it prevented any writing on discs), but in practice it has proven to be excellent.
Other technologies were developed by various vendors, including Ricoh's JustLink, Waste-Proof and
Safeburn from Yamaha, SMART-Burn from Lite-On, and Superlink from Mediatek, among others. For
a number of years, all recordable/rewritable drives have included some type of buffer underrun
protection. Buffer underrun protection technology involves having a special chipset in the drive that
monitors the drive buffer. When it anticipates that a buffer underrun might occur (the buffer is running
low on data), it temporarily suspends the recording until more data fills the buffer. When the buffer is
sufficiently restocked, the drive then locates exactly where the recording left off earlier and restarts
recording again immediately after that position.
According to the Orange Book specification, gaps between data in a recording must not be more than
100 milliseconds in length. The buffer underrun technology can restart the recording with a gap of 40-
45 milliseconds or less from where it left off, which is well within the specification. These small
gaps are easily compensated for by the error correction built into the recording, so no data is lost.
If both your drive and recording software supports buffer underrun protection, you can multitask—do
other things while burning discs—without fear of producing a bad recording.
Booting from a Floppy Disk with Optical Drive Support
To learn more about setting up a floppy disk with optical drive support, see Chapter 11 of
Upgrading
and Repairing PCs
, 19
th
Edition, included on the DVD packaged with this topic.
Bootable Optical Discs—El Torito
If your system BIOS is a version dated from 1998 or later, most likely it has “El Torito” support,
which means it supports booting from a bootable optical disc. The El Torito name comes from the
Phoenix/IBM Bootable CD-ROM Format Specification, which was actually named after the El Torito
restaurant located near the Phoenix Software offices where the two engineers who developed the
standard ate lunch. What El Torito means for the PC is the capability to boot from optical discs,
which opens several possibilities, including creating bootable rescue discs, booting from newer OS
discs when installing to new systems, creating bootable diagnostics and test discs, and more.
To create a bootable optical disc, ideally you need a burning application that allows the creation of
bootable discs. Additionally, in some cases you need a bootable floppy that contains the drivers to
support your CD drive in DOS mode (sometimes called real-mode drivers). The best source for these
drivers (if needed) is a Windows 98 or Me startup floppy, which can be generated by any Windows
98 or Me system. Windows 98/Me startup disks can be used because these have the DOS-level CD-
ROM support already configured and installed. If you don't have access to such a system to generate
the disk, you can download one from
www.bootdisk.com
.
