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IBM13Q4739CC
4M x 72 Registered SDRAM Module
08J0512.E24526
Released 4/98
IBM Corporation. All rights reserved.
Use is further subject to the provisions at the end of this document.
Page 7 of 56
Burst Mode Operation
Burst Mode operation is used to provide a constant flow of data to memory locations (Write cycle), or from
memory locations (Read cycle). Three parameters define Burst Mode operation: Burst sequence, burst
length, and operation mode. The burst sequence and burst length are programmable, and are determined by
address bits A0 - A3 during the Mode Register Set command. Operation mode is also programmable and is
set by address bits A7 - A10 and BS.
The burst type is used to define the order in which the burst data will be delivered or stored to the SDRAM.
Two types of burst sequences are supported, sequential and interleaved as shown in the table below.
The burst length controls the number of bits that will be output after a Read command, or the number of bits
to be input after a Write command. The burst length can be programmed to have values of 1, 2, 4, 8 or full
page (actual page length is dependent on organization: x4, x8, or x16). Full page Burst operation is only pos-
sible using the sequential burst type.
Burst operation mode can be normal operation or multiple burst with single Write operation. Normal operation
implies that the device will perform Burst operations on both Read and Write cycles until the desired burst
length is satisfied. Multiple burst with single Write operation was added to support Write Through Cache oper-
ation. Here, the programmed burst length only applies to Read cycles. All Write cycles are single Write oper-
ations when this mode is selected.
Note: Page length is a function of I/O organization and column addressing;
The x4 SDRAMs used on this DIMM have a Page Length = 1024 bits
Burst Length and Sequence
(This DIMM supports burst lengths of 2 only.)
Burst Length
Starting Address (A2 A1 A0)
Sequential Addressing (decimal)
Interleave Addressing (decimal)
2
x x 0
0, 1
0, 1
x x 1
1, 0
1, 0
4
x 0 0
0, 1, 2, 3
0, 1, 2, 3
x 0 1
1, 2, 3, 0
1, 0, 3, 2
x 1 0
2, 3, 0, 1
2, 3, 0, 1
x 1 1
3, 0, 1, 2
3, 2, 1, 0
8
0 0 0
0, 1, 2, 3, 4, 5, 6, 7
0, 1, 2, 3, 4, 5, 6, 7
0 0 1
1, 2, 3, 4, 5, 6, 7, 0
1, 0, 3, 2, 5, 4, 7, 6
0 1 0
2, 3, 4, 5, 6, 7, 0, 1
2, 3, 0, 1, 6, 7, 4, 5
0 1 1
3, 4, 5, 6, 7, 0, 1, 2
3, 2, 1, 0, 7, 6, 5, 4
1 0 0
4, 5, 6, 7, 0, 1, 2, 3
4, 5, 6, 7, 0, 1, 2, 3
1 0 1
5, 6, 7, 0, 1, 2, 3, 4
5, 4, 7, 6, 1, 0, 3, 2
1 1 0
6, 7, 0, 1, 2, 3, 4, 5
6, 7, 4, 5, 2, 3, 0, 1
1 1 1
7, 0, 1, 2, 3, 4, 5, 6
7, 6, 5, 4, 3, 2, 1, 0
Full Page (Note)
n n n
Cn, Cn+1, Cn+2,......
Not Supported