參數(shù)資料
型號: UPD488448FB-C80-45-DQ1
廠商: NEC Corp.
英文描述: 128 M-bit Direct Rambus⑩ DRAM
中文描述: 128 M位DRAM的直接Rambus的⑩
文件頁數(shù): 32/80頁
文件大?。?/td> 1902K
代理商: UPD488448FB-C80-45-DQ1
Data Sheet M14837EJ3V0DS00
32
μ
PD488448 for Rev. P
18. Interleaved RRWW - Example
Figure 18-1 shows a steady-state sequence of 2-dualoct RD/RD/WR/WR.. transactions directed to non-adjacent
banks of a single RDRAM. This is similar to the interleaved write and read examples in Figure 16-1 and Figure 17-1
except that bubble cycles need to be inserted by the controller at read/write boundaries. The DQ data pin efficiency
for the example in Figure 18-1 is 32/42 or 76%. If there were more RDRAMs on the Channel, the DQ pin efficiency
would approach 32/34 or 94% for the two-dualoct RRWW sequence (this case is not shown).
In Figure 18-1, the first bubble type t
CBUB1
is inserted by the controller between a RD and WR command on the COL
pins. This bubble accounts for the round-trip propagation delay that is seen by read data, and is explained in detail in
Figure 4-1. This bubble appears on the DQA and DQB pins as t
DBUB1
between a write data dualoct D and read data
dualoct Q. This bubble also appears on the ROW pins as t
RBUB1
.
The second bubble type t
CBUB2
is inserted (as a NOCOP command) by the controller between a WR and RD
command on the COL pins when there is a WR-WR-RD sequence to the same device. This bubble enables write
data to be retired from the write buffer without being lost, and is explained in detail in Figure 15-2. There would be no
bubble if address c0 and address d0 were directed to different devices. This bubble appears on the DQA and DQB
pins as t
DBUB2
between a write data dualoct D and read data dualoct Q. This bubble also appears on the ROW pins
as t
RBUB2
.
Figure 18-1 Interleaved RRWW Sequence with Two Dualoct Data Length
CTM/CFM
DQA7..0
DQB7..0
COL4
..COL0
ROW2
..ROW0
T
0
T
4
T
8
T
12
T
1
T
5
T
9
T
13
T
2
T
6
T
10
T
14
T
3
T
7
T
11
T
15
T
16
T
20
T
24
T
28
T
17
T
21
T
25
T
29
T
18
T
22
T
26
T
30
T
19
T
23
T
27
T
31
T
32
T
36
T
40
T
44
T
33
T
37
T
41
T
45
T
34
T
38
T
42
T
46
T
35
T
39
T
43
T
47
ACT a0
MSK (b2)
WRA c2
MSK (b1)
WR c1
WR b1
MSK (y2)
WRA b2
PREX a3
D (b2)
D (b1)
ACT b0
ACT c0
ACT d0
ACT e0
RD a1
RD a2
PREX z3
Q (a2)
Q (a1)
MSK (c1)
D (c1)
NOCOP
MSK (c2)
RDd0
D (c2)
t
RBUB1
RDf
Q (z2)
Q (z1)
D (y2)
RD z1
RD z2
t
CBUB1
t
DBUB1
t
DBUB1
t
DBUB2
t
CBUB2
t
RBUB2
t
CBUB2
NOCOP
f3 = {Da,Ba+2}
Transaction f: WR
f0 = {Da,Ba+2,Rf}
f1 = {Da,Ba+2,Cf1}
f2= {Da,Ba+2,Cf2}
e3 = {Da,Ba}
Transaction e: RD
e0 = {Da,Ba,Re}
e1 = {Da,Ba,Ce1}
e2= {Da,Ba,Ce2}
d3 = {Da,Ba+6}
Transaction d: RD
d0 = {Da,Ba+6,Rd}
d1 = {Da,Ba+6,Cd1}
d2= {Da,Ba+6,Cd2}
c3 = {Da,Ba+4}
Transaction c: WR
c0 = {Da,Ba+4,Rc}
c1 = {Da,Ba+4,Cc1}
c2= {Da,Ba+4,Cc2}
b3 = {Da,Ba+2}
Transaction b: WR
b0 = {Da,Ba+2,Rb}
b1 = {Da,Ba+2,Cb1}
b2= {Da,Ba+2,Cb2}
a3 = {Da,Ba}
Transaction a: RD
a0 = {Da,Ba,Ra}
a1 = {Da,Ba,Ca1}
a2= {Da,Ba,Ca2}
z3 = {Da,Ba+6}
Transaction z: RD
z0 = {Da,Ba+6,Rz}
z1 = {Da,Ba+6,Cz1}
z2= {Da,Ba+6,Cz2}
y3 = {Da,Ba+4}
Transaction y: WR
y0 = {Da,Ba+4,Ry}
y1 = {Da,Ba+4,Cy1}
y2= {Da,Ba+4,Cy2}
Transaction e can use the
same bank as transaction a
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