Southern California Distribution Issue 02 Part 02

Published in

· 5 years ago

  

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.