Page 106 - DCAP303_MULTIMEDIA_SYSTEMS

Multimedia Systems

notes However, a new large EIDE disk cannot always be connected to an old PC. The original IBM
programming interface limited the disk space to 528 megabytes (not a big problem when hard
disks had 10 or 20 megs). However, an old IDE disk interface chip may not support data beyond
the first 528 megs. You may need to load a new operating system (Windows 95, OS/2 or Windows
NT) and the partitions containing the operating system files may have to reside completely within
the first 528 megs of the disk.
Computers built in the last year should come with EIDE. The extensions overcome limits in the
original IDE design:
• The IDE supports only disks. The EIDE supports a mixture of disks, tapes and CD-ROM
drives.
• The IDE supports only two devices. The EIDE supports up to four devices on the same
controller chip although it uses two cables.

• The EIDE allows disks up to 1 gigabyte. Larger disks may also work, but that is up to the
vendor. The IBM, for example, does not officially support EIDE disks larger than one gig.

Since EIDE simulated two separate IDE interface chips, there is an optimization that many
customers do not fully appreciate. Newer operating systems (OS/2, Windows NT and even
Windows 95 to some extent) permit more than one I/O request to be running at a time. When
a program wants to read something from a disk, the request is given to the disk interface and
another program is allowed to run while the first program waits for data. However, the IDE
interface allows only one of the two disks connected to the same cable to be active at a time, and
any request to use the second disk will be blocked while data is being read from the first disk. An
EIDE interface duplicates this IDE restriction, but since the EIDE chip looks like two IDE devices,
a request can be made through the second interface while the first interface is busy.
If you run plain old DOS and Windows 3.x, it does not matter. Those systems will wait for any
operation to complete before running any other program. However, if you are running a new
system, and if you purchase a second IDE hard disk, then there is a performance advantage to
putting the second drive on the second interface cable (managed by the second simulated IDE
“device”) rather than connecting it to the same flat disk interface to which the first disk is connected.
On separate cables, the two disks can be active at the same time.
However, if you have two hard disks and an EIDE CD-ROM, then it is best to put the two disks
on the same cable and isolate the CD-ROM on the second cable. A CD-ROM is much slower than a
hard disk, and it will be busy longer. If it is on the same cable with a hard disk, it will block access
to that disk when any request is made. Unless it is used very infrequently, the best performance
will probably be provided by isolating the slow CD-ROM on its own cable.

The EIDE was adopted as a standard by ANSI in 1994 and also called as
Advanced Technology Attachment-2.

6.2.4 analogue telephone adapter (ata)
An analogue telephony adapter, or analogue telephone adapter (ATA) is a device used to connect
one or more standard analogue telephones to a digital telephone system (such as voice over IP)
or a non-standard telephone system.

An ATA usually takes the form of a small box with a power adapter, one Ethernet port, one or
more FXS telephone ports and may also have a FXO link. Users can plug one or more standard
analogue telephone devices into the ATA and the analogue device(s) will operate, usually
transparently, on a VoIP network.
The most common ATA is a box with at least one Foreign Exchange Station (which includes a
telephone jack), used to connect a conventional telephone, and an Ethernet jack used to connect

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