On page 39 of the September ’96 issue of Videomaker, you said that Windows 95 uses 16-bit
video components, but imply that it is also 32-bit in other ways. I’m confused by this statement. Could you
enlighten me, please?

John B. Cason
Internet

The designers of Windows 95 had a tough task: to make a 32-bit operating system that would run all
existing 16-bit DOS 6.22 applications. Since all 32-bit systems exchange data in 32-bit chunks, this
presented a problem.

Their solution was to create a system that switches nimbly between 16-bit and 32-bit
operations. Thus, when you load a 16-bit device driver in your Windows 95 config.sys file, the system
automatically operates that device in 16-bit mode.

This is why it’s possible to say, as David Brott did in the September issue, that Windows
95 is a 32-bit operating system that still relies on 16-bit components. If every piece of hardware in your
computer (graphics card, CD-ROM, video capture card, hard drive controller, etc.) had a 32-bit driver,
then Windows 95 would become a true 32-bit operating system. Most systems, however, still rely on 16-bit
drivers for at least a portion of their hardware.

Windows NT solves this problem with brutal elegance by simply refusing to operate any
hardware with a 16-bit driver. This was one of the reasons for the development of Windows 95: to create a
bridge between 16-bit and 32-bit versions of Windows, a bridge built of 32-bit device drivers and
applications.


What is a control track? What does it do? Where is it recorded? Who put it there? When do we use it? Why
don’t 8mm and Hi8 have one? I’m very confused. Can you put me on the right track?

Tharanga Ramanayake
Toronto, Canada

The term “control track” (sometimes abbreviated CTL) describes the linear strip of information that’s
recorded alongside the diagonal video tracks on a videotape. The purpose of the control track is to store
synchronization information (the “sync signal”) so that playback equipment–monitors, etc.–will be able to
decode the video signal correctly.

VHS and S-VHS tapes make use of linear control tracks; 8mm and Hi8 tapes, however,
use frequency modulation to store the sync signal along with the video and AFM audio signals in the same
diagonal tracks. This is why 8mm and Hi8 recordings don’t require a separate control track; the same
information is there, but it’s recorded differently.


I was shopping for an A/V optimized hard drive the other day when someone suggested that I use a RAID
system to store my digital video files. What’s a RAID system, and how does it work?

Chet Orland
Honolulu, Hawaii

A RAID (Redundant Array of Independent Disks) is a grouping of several standard hard disks with a
hardware RAID controller. When you use hard disks in this configuration, the whole becomes more
powerful than the sum of its parts; in addition to higher capacity, RAIDs offer faster data transfer rates
and increased data security than single-drive systems.


The most common form of RAID used in high-end digital video is a level-3 RAID. In this
system, all but one of the hard disks writes incoming digital information in 512-byte sectors, while the
additional hard disk writes a 512-byte parity sector for data verification. The RAID then groups these
sectors into a single super-sector, which becomes the minimum unit of data transfer into or out of the
system. In this way, the RAID allows several disks to operate at the same time, increasing the data
throughput considerably.


Recently, I bought a Panasonic Broadcast and Television Systems AG456 camcorder, but I’m running out
of storage space for these S-VHS tapes. I’m considering the purchase of a VHS-C cassette adapter so I can
use the more compact S-VHS-C tapes instead of the full-size version.
Would the use of this VHS-C system work well in my AG456? Can it harm my camcorder in any
way?

Lynden Brown
Nassau, Bahamas

Stop! Before you put that ordinary VHS-C adapter in your precious S-VHS camcorder, you should
know that these two pieces of equipment were not designed to work with one another. Whenever you put
anything into that delicate tape transport system that wasn’t intended to be there, you risk permanent
damage to the heads, pins, rollers, eject mechanism, etc. of your camcorder.

A story came to us once of an individual who attempted to do what you’re describing
with his S-VHS editing deck. When he tried to insert an S-VHS-C cassette, the adapter became inextricably
stuck in the tape transport, and the whole mess had to be shipped off to the manufacturer for
repairs.

For your storage problems, you might consider purchasing longer-playing S-VHS tapes.
Even though many professionals prefer shorter running times for greater reliability, high-quality 120-
minute S-VHS tapes work well for most situations. This is more than twice the capacity of the longest S-
VHS-C tape now available on the market.

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