k4r881869m Samsung Semiconductor, Inc., k4r881869m Datasheet - Page 12

• Manufacturer Part Number: k4r881869m
• Description: 288mbit Rdram 512k X 18 Bit X 2*16 Dependent Banks Direct Rdramtm
• Manufacturer: Samsung Semiconductor, Inc.

K4R881869M
DQ Packet Timing
Figure 4 shows the timing relationship of COLC packets
with D and Q data packets. This document uses a specific
convention for measuring time intervals between packets: all
packets on the ROW and COL pins (ROWA, ROWR,
COLC, COLM, COLX) use the trailing edge of the packet as
a reference point, and all packets on the DQA/DQB pins (D
and Q) use the leading edge of the packet as a reference
point.
An RD or RDA command will transmit a dualoct of read
data Q a time t
cycles of round-trip propagation delay on the Channel. The
t
values ( 8, 9, 10, 11, or 12 t
depends upon the number of RDRAM devices on the
Channel and the RDRAM timing bin. See Figure 39 for
more information.
COLM Packet to D Packet Mapping
Figure 5 shows a write operation initiated by a WR
command in a COLC packet. If a subset of the 16 bytes of
write data are to be written, then a COLM packet is trans-
mitted on the COL pins a time t
containing the WR command. The M bit of the COLM
packet is set to indicate that it contains the MA and MB
mask fields. Note that this COLM packet is aligned with the
COLC packet which causes the write buffer to be retired.
See Figure 17 for more details.
If all 16 bytes of the D data packet are to be written, then no
further control information is required. The packet slot that
would have been used by the COLM packet (t
COLC packet) is available to be used as an COLX packet.
This could be used for a PREX precharge command or for a
CAC
COL4
CTM/CFM
DQA8..0
ROW2
DQB8..0
..COL0
..ROW0
parameter may be programmed to a one of a range of
Figure 4: Read (Q) and Write (D) Data Packet - Timing for t
CAC
T
0
WR a1
T
This gap on the DQA/DQB pins appears automatically
1
later. This time includes one to five
T
2
T
3
T
4
t
RD b1
T
CYCLE
CAC
5
t
T
CWD
6
T
RTR
7
). The value chosen
T
8
T
after the COLC packet
9
T
10
D (a1)
T
11
T
12
T
13
RTR
T
t
14
CAC
T
15
after the
T
16
-t
Q (a1)
T
17
CWD
Q (a1)
• • •
• • •
T
18
Q (a1)
T
19
Page 10
Q (b1)
T
20
Q (b1)
T
21
A WR or WRA command will receive a dualoct of write
data D a time t
the round-trip propagation time of the Channel since the
COLC and D packets are traveling in the same direction.
When a Q packet follows a D packet (shown in the left half
of the figure), a gap (t
between them because the t
t
packets with the WR and RD commands which schedule the
D and Q packets.
When a D packet follows a Q packet (shown in the right half
of the figure), no gap is needed between them because the
t
t
packets with the RD WR commands by the controller so the
Q and D packets do not overlap.
housekeeping command (this case is not shown). The M bit
is not asserted in an COLX packet and causes all 16 bytes of
the previous WR to be written unconditionally. Note that a
RD command will never need a COLM packet, and will
always be able to use the COLX packet option (a read opera-
tion has no need for the byte-write-enable control bits).
Figure 5 also shows the mapping between the MA and MB
fields of the COLM packet and bytes of the D packet on the
DQA and DQB pins. Each mask bit controls whether a byte
of data is written (=1) or not written (=0).
T
CAC
CWD
CAC
22
T
23
T
value. There will be no gap between the two COLC
-t
24
value is less than the t
T
This gap on the COL pins must be inserted by the controller
CWD
25
RD c1
T
26
T
or greater must be inserted between the COLC
27
T
CAC
28
CWD
T
29
t
CAC
T
= 8, 9, 10, 11, or 12 t
30
later. This time does not need to include
T
31
-t
CAC
WR d1
T
• • •
CWD
32
WR d1
T
33
WR d1
-t
T
CWD
34
CAC
CWD
WR d1
T
35
Preliminary
Direct RDRAM
Rev. 0.9 Jan. 2000
WR d1
T
value is always less than the
value. However, , a gap of
36
) will automatically appear
T
37
• • •
Q (a1)
T
38
Q (c1)
T
39
CYCLE
Q (c1)
T
40
• • •
t
Q (c1)
T
CWD
41
Q (c1)
D (d1)
t
T
CAC
42
D (d1)
T
43
D (d1)
T
44
T
D (d1)
45
T
D (d1)
46
T
47
™