2: Technical Background
Page 5
Kenwood 72X and 62X TrueX User’s Guide
2: Technical Background
EIDE/ATAPI BASICS
"EIDE" stands for enhanced integrated drive electronics. It is a pathway to
transfer data from an attached device (such as a hard disk or CD-ROM drive)
to the computer's processor. It was created originally for hard disk drives and
could attach either one or two devices at a time. It became widely used by the
majority of computer manufacturers because of its ease of use, compatibility
and its inexpensive nature.
The CD-ROM drive that you are about to install is "ATAPI", which is simply a
subset of the "EIDE" specification. Despite some subtle differences, in this manual
we will use the terms "IDE", "EIDE" and "ATAPI" interchangeably unless noted.
PRIMARY AND SECONDARY CHANNELS AND “CHAINING”
In most systems, EIDE allows you to attach a total of four devices to your computer.
It accomplishes this by having two channels, PRIMARY and SECONDARY, and each
channel is capable of connecting or "chaining" two devices (i.e. 2 channels x 2
devices/channel = total of 4 devices). A "chain" consists of two devices connected
with one cable. This IDE cable will have a connector at each end and it will usually
have an additional connector in the middle.
MASTER, SLAVE, AND CABLE SELECT
Because EIDE allows two devices to be connected to one cable, it needs to
distinguish between the two devices so it can communicate separately with each
device. EIDE achieves this by recognizing a device as either a MASTER or a
SLAVE, indicated on the drive as “MA” and “SL”, respectively. So, if two devices
are connected to a single channel, one device must be set to MASTER and the
other must be set to SLAVE. If only one device is attached to a channel, it must
be set to MASTER. Finally, MASTERS and SLAVES are not assigned to specific
connectors on the IDE cable, so order of connection does not matter.
KW-40 72/62X atapi manual 12/13/99 3:25 PM Page 7
