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Chapter 3 Media Changer Commands

Read Buffer Command (3Ch)

124 Quantum ATL SuperLoader Software Interface Guide

The READ BUFFER command will return the same number of

bytes of data as received in the prior echo buffer mode WRITE

BUFFER command from the same initiator. If a prior Echo Buffer

mode WRITE BUFFER command was not successfully completed,

the Echo Buffer mode READ BUFFER command will terminate

with a CHECK CONDITION status, the sense key shall be set to

ILLEGAL REQUEST and the additional sense code to COMMAND

SEQUENCE ERROR. If the data in the Echo Buffer has been

overwritten by another initiator the drive will terminate the

command with a CHECK CONDITION status, the sense key will

be set to ABORTED COMMAND and the additional sense code to

ECHO BUFFER OVERWRITTEN.

Echo Buffer

Descriptor Mode

(1011b)

In this mode, a maximum of four bytes of READ BUFFER

descriptor information is returned. The device will return the

descriptor information for the Echo Buffer. The Buffer Offset field

is reserved in this mode. The allocation length should be set to four

or greater. The device shall transfer the lesser of the allocation

length or four bytes of READ BUFFER descriptor.

Figure 62 Echo Buffer

Descriptor

Bit

Byte76543210

Reserved EBOS

Reserved

Reserved Buffer Capacity

Buffer Capacity

1 2 ... 137 138 139 140 141 142 143 144 145 146 147 ... 195 196

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Quantum SuperLoader Guida Utente Pagina 142