Integrated Silicon Solution, Inc. — www.issi.com —
1-800-379-4774
15
Rev. 00D
06/02/08
IS42S32200E
BURST DEFINITION
Burst Starting Column Order of Accesses Within a Burst
Length Address Type = Sequential Type = Interleaved
A0
2 0 0-1 0-1
1 1-0 1-0
A1 A0
0 0 0-1-2-3 0-1-2-3
4 0 1 1-2-3-0 1-0-3-2
1 0 2-3-0-1 2-3-0-1
1 1 3-0-1-2 3-2-1-0
A2 A1 A0
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
8 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 n = A0-A7 Cn, Cn + 1, Cn + 2 Not Supported
Page Cn + 3, Cn + 4...
(y) (location 0-y) …Cn - 1,
Cn…
Burst Length
Read and write accesses to the SDRAM are burst ori-
ented, with the burst length being programmable, as
shown in MODE REGISTER DEFINITION. The burst
length determines the maximum number of column loca-
tions that can be accessed for a given READ or WRITE
command. Burst lengths of 1, 2, 4 or 8 locations are
available for both the sequential and the interleaved burst
types, and a full-page burst is available for the sequential
type. The full-page burst is used in conjunction with the
BURST TERMINATE command to generate arbitrary
burst lengths.
Reserved states should not be used, as unknown opera-
tion or incompatibility with future versions may result.
When a READ or WRITE command is issued, a block of
columns equal to the burst length is effectively selected.
All accesses for that burst take place within this block,
meaning that the burst will wrap within the block if a
boundary is reached. The block is uniquely selected by
A1-A7 (x32) when the burst length is set to two; by A2-A7
(x32) when the burst length is set to four; and by A3-A7
(x32) when the burst length is set to eight. The remaining
(least significant) address bit(s) is (are) used to select the
starting location within the block. Full-page bursts wrap
within the page if the boundary is reached.
Burst Type
Accesses within a given burst may be programmed to be
either sequential or interleaved; this is referred to as the
burst type and is selected via bit M3.
The ordering of accesses within a burst is determined by
the burst length, the burst type and the starting column
address, as shown in BURST DEFINITION table.