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4–44
Clocks, Cache, and External Interface
29 September 1997 – Subject To Change
System-Initiated Transactions
When using the pipelined SSRAMs, the data output register delays the data an addi-
tional sysclk cycle. When the CBOX_CONFIG<BC_REG_REG> bit is set, the
data_ram_oe_l deassertion is delayed an additional sysclk cycle to allow the system
ample time to sample the delayed Bcache read data.
Figure 4–21 READ Timing Diagram (Bcache Hit) Flow-Through SSRAM
FM-05570.AI4
data_h<127:0>
index_h<21:4>
tag_ram_oe_l
tag_ram_we_l
sys_clk
012345678
9
1
01
11
2
1
4
13
15
16
17
18
19
20
addr_bus_req_h
addr_h<39:4>
A0
cmd_h<3:0>
READ
addr_res_h<1:0>
ACKBC
D00
D01
D02
D03
dack_h
st_clk
x
_h
bc_clk_delay
A0
bc_rd_latency
A0
tag_data_h<32:19>
T0
tag_dirty_h
D
tag_valid_h
V
data_adsc_l
data_adv_l
data_ram_oe_l
data_ram_we_l<3:0>
F
012345678
9
1
01
11
2
1
4
13
15
16
17
18
19
20