HY[B/E]18L256160B[C/F]X-7.5
256-Mbit Mobile-RAM
Functional Description
Field Bits Type Description
BL
[2:0]
w
Burst Length
000 1
001 2
010 4
011 8
111 full page (Sequential burst type only)
Note:All other bit combinations are RESERVED.
2.2.1.1
Burst Length
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.
Table 5
Burst Definition
Burst Length
Starting Column Address
Order of Accesses Within a Burst
A2
A1
A0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
n
Sequential
0 - 1
Interleaved
0 - 1
2
4
1 - 0
1 - 0
0
0
1
1
0
0
1
1
0
0
1
1
n
0 - 1 - 2 - 3
1 - 2 - 3 - 0
2 - 3 - 0 - 1
3 - 0 - 1 - 2
0 - 1 - 2 - 3
1 - 0 - 3 - 2
2 - 3 - 0 - 1
3 - 2 - 1 - 0
8
0
0
0
0
1
1
1
1
n
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, …
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
Full Page
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.
Data Sheet
9
Rev. 1.11, 2007-01
07142005-CR47-RB2E
QIMONDA [ QIMONDA AG ]
