HP 9800 SERIES Service Manual

A-4 HP 9895A Disc Memory Command Set
Target Addressing
Each unit has a target address associated with it. This is the logical address of the next sector
which
will be accessed by a Data Transfer command or return for an address request. This
sector is referred
to as the target sector. It is uniquely determined by a target cylinder
address, a target
head address and a target sector address.
Following a
power up or a Clear command, the target address will be set to cylinder 0, head
° and sector ° for HP format and 1 for IBM format.
A
Seek command sets the target address to the cylinder, head and sector indicated in the
command sequence.
During a
data transfer, the target address is automatically updated so the successive logical
sectors
can be read without issuing a seek to each sector. This includes updates which cross
track
or cylinder bounds. The 9895A is always in cylinder mode; that is, the head address
will be incremented before the cylinder address.
If a data transfer terminates abnormally, the target address is left pointing at the sector which
caused the termination.
The D Bit
Each sector has a flag called the D bit. It is used to indicate that' a track is defective (which is
different than invisible). The D bit can be set or cleared using the Initialize command. A set D
bit affects the Read, Write
and Format commands and is indicated in the returned status.
The Format
command is used to convert all tracks flagged with the D bit into invisible tracks.

HP 9800 SERIES Specifications

General

Category	Storage
Series	9800 SERIES
Type	Disk Array
Drive Types Supported	SAS, SSD
RAID Levels Supported	0, 1, 5, 6, 10
Host Connectivity	Fibre Channel, iSCSI, SAS
Redundancy	Redundant power supplies and fans