115
Bit:
7
6
5
4
3
2
1
0
Bit name:
—
—
—
—
—
—
—
—
Initial value:
0
0
0
0
0
0
0
0
R/W:
—
—
—
—
—
—
—
—
•
Bit 15 (Dual-CAS or Dual-WE Select Bit (CW2)): When accessing a 16-bit bus width space,
CW2 selects the dual-CAS or the dual-WE method. When cleared to 0, the
CASH
,
CASL
, and
WRL
signals are valid ; when set to 1, the
CASL
,
WRH
, and
WRL
signals are valid. When
accessing an 8-bit space, only
CASL
and
WRL
signals are valid, regardless of the CW2
setting.
Bit 15L: CW2
Description
0
Dual-CAS:
CASH
,
CASL
, and
WRL
signals are valid
(Initial value)
1
Dual-WE:
CASL
,
WRH
, and
WRL
signals are valid
•
Bit 14 (RAS Down (RASD)): When DRAM access pauses, RASD determines whether to keep
RAS
low while waiting for the next DRAM access (RAS down mode) or return it to high
(RAS up mode). When cleared to 0, the
RAS
signal returns to high; when set to 1, it stays low.
Bit 14: RASD
Description
0
RAS up mode: Return
RAS
signal to high and wait for the next DRAM
access
(Initial value)
1
RAS down mode: Keep
RAS
signal low and wait for the next DRAM
access
•
Bit 13 (RAS Precharge Cycle Count (TPC)): TPC selects whether the
RAS
signal precharge
cycle (TP) will be 1 state or 2. When TPC is cleared to 0, a 1-state precharge cycle is inserted;
when 1 is set, a 2-state precharge cycle is inserted.
Bit 13: TPC
Description
0
1-state precharge cycle inserted
(Initial value)
1
2-state precharge cycle inserted
•
Bit 12 (Burst Operation Enable (BE)): BE selects whether or not to perform burst operation, a
high-speed page mode. When burst operation is not selected (0), the row address is not
compared but instead is transferred to the DRAM every time and full access is performed.
When burst operation is selected (1), row addresses are compared and burst operation with the
same row address as previously is performed (in this access, no row address is output and the
column address and
CAS
signal alone are output) (high-speed page mode).
Содержание HD6417032
Страница 21: ......
Страница 35: ...xiv ...
Страница 85: ...50 ...
Страница 101: ...66 ...
Страница 129: ...94 ...
Страница 135: ...100 ...
Страница 343: ...308 ...
Страница 369: ...334 ...
Страница 383: ...348 ...
Страница 475: ...440 ...
Страница 525: ...490 CK RAS CAS TRp TRc TRcc tRASD1 tRASD2 tCASD3 tCASD2 TRr tCSR Figure 20 18 Self Refresh ...
Страница 578: ...543 CK RAS CAS TRp TRc TRcc tRASD1 tRASD2 tCASD3 tCASD2 TRr tCSR Figure 20 62 Self Refresh ...
Страница 689: ...654 ...