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Message Format SDLT 600 SCSI Interface Guide

3-2 January 2005 81-81200-02 REV A01

The first byte of the message, as defined in Table 3-1, determines the format of the message.

Two-byte messages consist of two consecutive bytes. The value of the first byte, as defined in

Table 3-1, determines which message will be transmitted. The second byte is a parameter byte that is

used as defined in the message description.

A value of 1 in the first byte indicates the beginning of a multiple-byte extended message. The

minimum number of bytes sent for an extended message is three. The extended message format is

shown in Figure 3-1, and the data fields are described in Table 3-2.

Figure 3-1. Extended Message — Data Format

Table 3-1. SCSI Message Format

Message Code Message

00h One-byte message (TASK COMPLETE)

01h Extended message

02h – 1Fh One-byte message

20h – 2Fh Two-byte message

30h – 54h Reserved

55h One-byte message

56h – 7Fh Reserved

80h – FFh One-byte message (IDENTIFY)

Bit

Byte

7 6 5 4 3 2 1 0

0 Extended Message (01h)

1 Extended Message Length

Extended Message Code

3 to n-1 Extended Message Arguments

1 2 ... 25 26 27 28 29 30 31 32 33 34 35 ... 293 294

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Quantum 1200 Series DAT Autochanger Podręcznik Użytkownika Strona 30