Space 11H - Sony DDS-4 Product Description Manual

6. COMMAND SPECIFICATION

6. 24 SPACE 11h

Bit 7
Byte
0
1
2 (MSB)
3
4
5 Unused (00b)
SPACE provides a variety of positioning functions that are determined by the Code and Count fields in the Command
Descriptor Block.Å Both forward (toward EOM/P) and reverse (toward BOM/P) positioning are provided.
Code: The supported values are:
Note: The drive will reject a SPACE Setmark command if it has not configured through MODE SELECT to report
Setmarks. The drive will return a CHECK CONDITION status with the Sense data set to ILLEGAL REQUEST.
Note: In this command description the word "mark" is used to mean Filemark or Setmark. Only where their responses
differ shall Filemark and Setmark be referred to explicitly.
Count:
When spacing over blocks or marks, the Count field is interpreted as follows:
A positive value N causes forward movement over N blocks or marks. The tape is logically positioned after the Nth
block (or mark) on the EOM/P side.
A zero value causes no change in the logical position.
A negative value -N (2's complement notation) causes reverse movement over N blocks or marks. The tape is
logically positioned on the BOM /P side of the Nth block (or mark).
When spacing to EOD, the Count field is ignored. Forward movement occurs until the drive encounters EOD. The
position is such that a subsequent WRITE command would append data after the last entity that has been written to
tape before EOD.
When executing a SPACE, the drive implements the following hierarchy:
Blocks (lowest), Filemarks, Setmarks, EOD, BOM/P or EOM/P (highest)
Therefore, SPACE N blocks will halt with GOOD status after the Nth block, or with CHECK CONDITION status on
any occurrence of Filemark, Setmark, EOD, BOM/P or EOM/P. A SPACE N filemarks will halt on the Nth filemark or
on any occurrence of setmark, EOD, BOM/P or EOM/P, and so on. Within the Sense data, the fields will be set as
described on the following table.
6 - 92 SONY SDT-10000/SDT-11000 DDS Tape Drive
6 5
Logical Unit Number
Code
000b
001b
011b
100b
Table 6-53: SPACE codes
4 3
Operation Code (11h)
Reserved
Count
Reserved
Description
Blocks
Filemarks
End-Of-Data
Setmarks
SPACE
2 1 0
Code
(LSB)