Datasheet

1.4 Drive Operation on the Loop
C141-C008 1-25
(2) AL_PA
This sub-section describes the addresses (AL_PA) used on the loop.
AL_PA is an 8-bit character and when encoded to 10 bits, AL_PA has an equal
number of ones or zeros to maintain neutral running disparity.
Table 1.18 shows the AL_PA values and the priority used on the loop.
Details of AL_PA is described in Table 1.16.
Table 1.18 AL_PA value/priority
Values (hex) Priority & Use
00 Highest priority and assigned for FL_port.
The drive does not assume the existence of this value on the loop.
(because of assuming private loop)
01-EF 126 valid NL_Port address
01 (highest priority) < ===== > EF (Lowest priority)
F0 Has no priority and used for fairness algorithm and for Loop
Initialization process
F1-F6 not used
F7, F8 reserved for Loop initialization
FF vendor Specific reset
others not used
Most common method for the disk drive will be to have the backpanel provide a
hard assigned address.
If the drive failed to obtain a hard assigned address, the drive would obtain the
address by soft assigned method. For details, refer to sub-section (5).
(3) LIP (Loop Initialization on Primitive)
Loop Initialization is generated by sending any LIPs in Table 1.19.
The NL_Port which received a LIP then transmit the LIP to the next port on the
loop.
This cycle terminates when the NL_Port that started the initialization process
receives the LIP.