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Southern California Distribution Issue 02 Part 02
Optical Devices: A Technical Look
Optical devices are fairly new to the industry, although it has
been used long before it is used for computing purposes. This article
will provide the technical references and other information to these
devices.
CD-ROM
CD's has been with us for quite a long time, but it is relatively new
to the computing market. CD-ROM is the most common, and the best known
of the three types of optical devices. This type of system has many advantages
as well as disadvantages. In the BBS world, CD-ROM is virtually useless for
pirates, and only useful on PD systems, but when it comes to the distribution
area, nothing beats CD-ROM. A very cheap, compact solution to distribute large
amounts of data. It is mainly used in the reference area, and some games
that are planned by Sierra. Access Software also sells their software on CD's.
There are three different storage standards for Graphics/Audio, CD-AUDIO,
DVI, and XA. CD-AUDIO is the most commonly used format, and is the most
wasteful format, as it can only store a little more than an hour of audio.
XA and DVI are better solutions, and right now, seems like DVI is taking the
lead, and more people are supporting it. We shall see, if either one successes
in dominating the CD-ROM market, we'll have good pleasure of listening when
we're playing games, but most games do not even pass the 1.5 meg mark, and
a CD-ROM would be rediculous right now. Recommended CD-ROM drives should be
200 millisecond seek time.
WORM
WORM, useful for archive storage, and extremely effective for Pirate
systems. The usual size for these Write-Once drives is 800 Megabytes.
With an average seek time of 80ms and transfer rate of at least 5 MB per
second, it seems like an odd combination, but it is perfectly suitable for
BBS's. With empty cartriges at 160 dollars, it is a bargain compared to hard
drives. There isn't any standard for WORM drives, but the standard driver is
usually the same in function, and therefore not much difference except the
cartriges must be bought from the same company. Best source to obtain WORM
drives is Maxtor/Storage Dimensions. They are in a cooperate effort with Richo
in the production of WORM drives, and the drives are assemble in Japan, and
the controllers accompanying are True-SCSI controllers, from Future Domain.
Erasable Opticals (Magneto Optics)
The most rare of the three types of opticals, the most expensive, largest
storage around(1.2 Gig), and with a fast seek time(30 - 35ms), along with an
extremely fast transfer rate, thanks to SCSI for its superior performance.
These opticals are rewritable, and therefore useful for multipurpose work.
The drives actually has two heads, one for erasure, and one for read/write.
In order for the drive to write data, it must first move the erasure head
to the sector, heat the surface with laser to 200 degrees celcius, and with a
little work with the magnetic head, data can be written on it. These drives
have a minimum life of 10 years, and the discs are 260 dollars a piece, with
a 10 year MTBF. The standard for 5.25 inch Erasable Opticals is already set
back in 1988, and that ensures the disks are compatible with the drives which
follow the ISO standard. The future looks bright for these drives, and
eventually they'll replace the Hard Disks, and no more worries of disk crashes!
Again, the best source for these drives is Maxtor/Storage Dimensions.
More Information In TSCDR #3, Will Cover Polymer Type Drives, Tandy THOR.
