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Interface Information
2-1.
INTRODUCTION
This chapter describes the implementation of the
Enhanced Small Device Interface (ESDI) on the
disc drive mechanisms. Also included at the end
of this section is information on the CS/80
Command Set implementation, request status sum-
mary and utility command summary. Included is
the ESDI information specific to these products, as
well as a discussion of operating features designed
to improve system performance. The information
in this chapter is intended to give the user an in-
sight into how the product operates within the
ESDI environment.
The disc drives conform fully to the specifications
defined in the following industry-standard docu-
ment:
Enhanced
Small
Device
Interface
Specification (REV F).
It is assumed that the
reader is thoroughly familiar with the general
operation of ESDI as defined in the specification.
When
used
in
conjunction
with
the
ESDI
specification, this chapter provides the additional
information necessary to successfully communicate
with the drive 'Over ESDI.
NOTE
To maintain consistency with standard
ESDI terminology, the term "drive" is
used to refer to the disc mechanism in
this chapter.
2-2.
SUPPORTED ESDI FEATURES
The disc drives support the following standard
ESDI features:
• Serial Mode Operation
• 10 Megabit Per Second Transfer Rate
• Configuration Reporting
• Drive Hard Sectoring
• Daisy Chain Configuration (up to 7 drives)
• Power-On Sequencing
• Track Offsets
• Internal Self-Test Diagnostics
• Media Defect List
2-3.
DRIVE INTERFACE
CHARACTERISTICS
2
The drive complies with the physical interface
characteristics defined in the ESDI specification.
Refer to the specification for cabling requirements
and connector pin assignments. The physicalloca-
tion of the two interface, one power and one
ground connectors are shown in figure 6-1. (For
clarity, the power connector pin assignments are
also shown.)
The drive electrical interface circuits conform to
the specified electrical requirements. The drive uses
the 220/330-ohm termination option to terminate
all control signals originating at the controller.
2-4.
INTERFACE SIGNALS
The serial-mode use of all data and control signal
lines is defined in the ESDI specification. The fol-
lowing paragraphs include additional product-
specific considerations regarding the use of each
signal line. Tables 2-1, 2-2 and 2-3 provide response
bit information.
• DRIVE SELECT LINES. The drive responds
to selection by asserting its DRIVE SELECTED
line within 250 nanoseconds (see figure 2-1).
When selecting a drive, the controller must en-
sure that all drive select lines change within less
than 100 nanoseconds. This precludes any un-
desired drive selection during transition of the
drive select lines.
2-1
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