Samsung M9T manual Sata II Interface, Sata Terminology

CHAPTER 6 SATA II INTERFACE

6.1Introduction

The Spinpoint M9T disk drive is equipped with an industry standard SATA Interface fully supports and enhances PC mass storage requirements. The SATA interface conforms to the Serial ATA standards in Cabling, in Physical Signals, and in Logical Programming schemes. The Spinpoint M9T disk drive joins the industry premiere VLSI circuitry with ingenious programming skill that does not compromise performance or reliability. Seagate integrates and delivers the cutting edge in technology. Samsung Spinpoint M9T SATA class disk drives are designed to relieve and to enhance the I/O request processing function of system drivers.

6.1.1SATA Terminology

The following contains some commonly proposed terminology used in SATA technology.

BACKCHANNEL-A term used to describe or refer to the transmit same-side of SATA interface, when the scope of the paragraph is addressing the receive interface. For example, when discussing the receive SATA interface on the device side, the term “backchannel” would be used to describe the transmit interface on the device side.

CHARACTER ALIGNMENT-Character alignment is a receiver action that resets the character boundary to that of the comma sequence found in the K28.5 control character of the ALIGN primitive, and establishes Dword synchronization of the incoming serial data stream.

CHARACTER SLIPPING-Character slipping is the receiver action that realigns the receiver’s clock to the received bit stream by adding or removing bit times within the characters of the ALIGN primitive.

CODE VIOLATION- A code violation is an error that occurs in the reception process as a result of (1) a running disparity violation or (2) an encoded character that does not translate to a valid data or control character or (3) an encoded character that translates to a control character other than K28.5 or K28.3 in byte 0 of a Dword or (4) an encoded character that translates to any control character (valid or invalid) in bytes 1-3 of a Dword.

COMMA CHARACTER- A comma character is a control character, that when encoded, contains the comma sequence. In Serial ATA the only comma character used is K28.5, and only the ALIGN primitive contains the comma character. The comma sequence is the first seven bits of the encoded character.

COMMA SEQUENCE- The comma sequence is a seven-bit sequence of 0011111 or 1100000 in an encoded stream. The comma sequence is unique in that it appears only in a single encoded character, and furthermore, cannot appear in any subset of bits in adjacent encoded characters. This unique property allows the comma sequence to be used for determining alignment of the received data stream.

COMRESET / COMINIT- Host: Signal from the out of band detector that indicates the COMINIT out of band signal is being detected.

CONTROL CHARACTER- A control character is a combination of a byte value with the control variable equal to K.

CONTROL VARIABLE-The control variable, Z, is a flag that determines the code set to be used to interpret a data byte. The control variable has the value D (for data characters) or K (for control characters).

CRC-In Serial ATA a 32-bit CRC is calculated over the contents of a FIS. The Serial ATA CRC is the Dword in a frame that immediately precedes the EOF primitive.

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