HY[B/E]18L128160B[C/F]-7.5
128-Mbit Mobile-RAM
Functional Description
Data Sheet
13
V1.4, 2004-04-30
2.2.1.1
READ and WRITE accesses to the Mobile-RAM are burst oriented, with the burst length being programmable. The
burst length determines the maximum number of column locations that can be accessed for a given READ or
WRITE command. Burst lengths of 1, 2, 4, 8 locations are available for both the sequential and interleaved burst
types, and a full-page burst mode is available for the sequential burst type.
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 wraps within the block if a boundary
is reached. The block is uniquely selected by A1-A8 when the burst length is set to two, by A2-A8 when the burst
length is set to four and by A3-A8 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. Please note that full page bursts do not self-
terminate; this implies that full-page read or write bursts with Auto Precharge are not legal commands.
Burst Length
Notes
1. For a burst length of 2, A1-Ai select the two-data-element block; A0 selects the first access within the block.
2. For a burst length of 4, A2-Ai select the four-data-element block; A0-A1 select the first access within the block.
3. For a burst length of 8, A3-Ai select the eight-data-element block; A0-A2 select the first access within the block.
4. For a full page burst, A0-Ai select the starting data element.
5. Whenever a boundary of the block is reached within a given sequence, the following access wraps within the
block.
2.2.1.2
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 A3. The ordering of accesses within a burst is determined by the burst length, the
burst type and the starting column address, as shown in
Table 5
.
Burst Type
Table 5
Burst Length
Burst Definition
Starting Column Address
A2
A1
Order of Accesses Within a Burst
A0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
n
Sequential
0 - 1
1 - 0
0 - 1 - 2 - 3
1 - 2 - 3 - 0
2 - 3 - 0 - 1
3 - 0 - 1 - 2
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, Cn+1, Cn+2, …
Interleaved
0 - 1
1 - 0
0 - 1 - 2 - 3
1 - 0 - 3 - 2
2 - 3 - 0 - 1
3 - 2 - 1 - 0
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
2
4
0
0
1
1
0
0
1
1
0
0
1
1
n
8
0
0
0
0
1
1
1
1
n
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