
319
3.4.23 Agent Status Register at 5Ch
There are four command block agents. Each agent has State, DrBll and UnStEn status bits and Dead, Rst, DrBClr
and USEClr control bits. This register defaults to 0000 0000h and is cleared to 0000 0000h on a bus reset.
BITS
ACRONYM
DIR
DESCRIPTION
01
State0
R/O
State of the command block agent0. State0 shows the state of each command block agent 0.
00: Reset, 01: Active, 10: Suspended, 11: Dead.
2
DrBll0
R/O
DoorBell variable of the command block agent0. When the DOORBELL register receives a quadlet write
request, DrBll0 is set to 1. When the host writes 1 on DrBClr0, DrBll0 is set to 0.
3
UnStEn0
R/O
Unsolicited status enable variable of the command block agent0. When the UNSOLICITED_STATUS_EN-
ABLE register receives a quadlet write request, UnStEn0 is set to 1. If USTlEn in the agent control register (50h)
is set to 1, the transmission of a packet with tLabel (tl=111b+AgtNmb+ 0 or 1, where 0 or 1 is determined by the
host) clears UnStEn0. When the host writes 1 to USEClr0, USEClr0 is cleared.
4
Dead0
S/C
Dead state control bit. When Dead0 is set to 1, State0 is set to 11b.
5
Rst0
S/C
Reset state control bit. When Rst0 is set to 1, State0 is set to 00b.
6
DrBClr0
S/C
DoorBell variable clear bit. When DrBClr0 is set to 1, DrBll0 is set to 0.
7
USEClr0
S/C
Unsolicited status enable variable clear bit. When USEClr0 is set to 1, UnStEn0 is cleared.
89
State1
R/O
Functionality is the same as State0.
10
DrBll1
R/O
Functionality is the same as DrBll0.
11
UnStEn1
R/O
Functionality is the same as UnStEn0.
12
Dead1
S/C
Functionality is the same as Dead0.
13
Rst1
S/C
Functionality is the same as Rst0.
14
DrBClr1
S/C
Functionality is the same as DrBClr0.
15
USEClr1
S/C
Functionality is the same as USEClr0.
1617
State2
R/O
Functionality is the same as State0.
18
DrBll2
R/O
Functionality is the same as DrBll0.
19
UnStEn2
R/O
Functionality is the same as UnStEn0.
20
Dead2
S/C
Functionality is the same as Dead0.
21
Rst2
S/C
Functionality is the same as Rst0.
22
DrBClr2
S/C
Functionality is the same as DrBClr0.
23
USEClr2
S/C
Functionality is the same as USEClr0.
2425
State3
R/O
Functionality is the same as State0.
26
DrBll3
R/O
Functionality is the same as DrBll0.
27
UnStEn3
R/O
Functionality is the same as UnStEn0.
28
Dead3
S/C
Functionality is the same as Dead0.
29
Rst3
S/C
Functionality is the same as Rst0.
30
DrBClr3
S/C
Functionality is the same as DrBClr0.
31
USEClr3
S/C
Functionality is the same as USEClr0.