Seagate Medalist ST31082A, Product Manual

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Technical Reference Manual Page 23
Host Interface
5
About the Host Interface
The interface between the drive adapter and the drive is called the host
interface. The set of registers in the I/O space of the host that are controlled
through the host interface is known as the task file.
The physical interface from the drive to the host is called the task file
interface and is implemented using a 40-pin connector. The pin assignments
were described in chapter 4.
Definitions of signals are listed beginning on the next page under Signal
Descriptions.
Signal Conventions
The following conventions are used in the discussions that follow:
• All signals on the host interface shall have the prefix HOST.
• All negatively-active signals shall be further prefixed with a “-” designation.
• All positive-active signals shall be prefixed with a “+” designation.
• Signals whose source is the host are said to be “outbound” and those whose
source is the drive are said to be “inbound.”
Signal Levels
All signal levels are TTL compatible. A logic “1” is >2.0 Volts. A logic “0” is from
0.00 Volts to 0.70 Volts. The drive capability of each of the inbound signals is
described below.