is42s16800a-7tli Integrated Silicon Solution, Inc., is42s16800a-7tli Datasheet - Page 25

• Manufacturer Part Number: is42s16800a-7tli
• Description: 16meg X 8, 8meg X16 & 4meg X 32 128-mbit Synchronous Dram - Integrated Silicon Solution, Inc
• Manufacturer: Integrated Silicon Solution, Inc.

IS42S81600A, IS42S16800A, IS42S32400A
BURST LENGTH
Read and write accesses to the SDRAM are burst oriented,
with the burst length being programmable, as shown in
MODE REGISTER DEFINITION. The burst length deter-
mines the maximum number of column locations 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 com-
mand to generate arbitrary burst lengths.
Reserved states should not be used, as unknown operation
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, mean-
BURST DEFINITION
Burst
Integrated Silicon Solution, Inc. — www.issi.com —
PRELIMINARY INFORMATION Rev. 00C
01/20/05
Burst
Length
Page
Full
(y)
2
4
8
(location 0-y)
n = A0-A7
A 2
0
0
0
0
1
1
1
1
Starting Column
A d d r e s s
A 1
A 1
0
0
1
1
0
0
1
0
0
1
1
1
A 0
A 0
A 0
0
1
0
1
0
1
0
1
1
0
1
0
1
0
Type = Sequential
Cn, Cn + 1, Cn + 2
Cn + 3, Cn + 4...
0-1-2-3-4-5-6-7
1-2-3-4-5-6-7-0
2-3-4-5-6-7-0-1
3-4-5-6-7-0-1-2
4-5-6-7-0-1-2-3
5-6-7-0-1-2-3-4
6-7-0-1-2-3-4-5
7-0-1-2-3-4-5-6
…Cn - 1,
0-1-2-3
1-2-3-0
2-3-0-1
3-0-1-2
Cn…
0-1
1-0
1-800-379-4774
ing 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.
Order of Accesses Within a
Type = Interleaved
0-1-2-3-4-5-6-7
1-0-3-2-5-4-7-6
2-3-0-1-6-7-4-5
3-2-1-0-7-6-5-4
4-5-6-7-0-1-2-3
5-4-7-6-1-0-3-2
6-7-4-5-2-3-0-1
7-6-5-4-3-2-1-0
Not Supported
0-1-2-3
1-0-3-2
2-3-0-1
3-2-1-0
0-1
1-0
ISSI
25
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