EtronTech
EM636327
The mode register is divided into various fields depending on functionality.
· Burst Length Field (A2~A0)
This field specifies the data length of column access using the A2~A0 pins and selects the
Burst Length to be 1, 2, 4, 8, or full page.
A2
0
A1
0
A0
0
Burst Length
1
0
0
1
2
0
1
0
4
0
1
1
8
1
0
0
Reserved
Reserved
Reserved
Full Page
1
0
1
1
1
0
1
1
1
·
Addressing Mode Select Field (A3)
The Addressing Mode can be one of two modes, Interleave Mode or Sequential Mode.
Sequential Mode supports burst length of 1, 2, 4, 8, or full page, but Interleave Mode only
supports burst length of 4 and 8.
A3
0
Addressing Mode
Sequential
1
Interleave
--- Addressing Sequence of Sequential Mode
An internal column address is performed by increasing the address from the column
address which is input to the device. The internal column address is varied by the Burst
Length as shown in the following table. When the value of column address, (n + m), in
the table is larger than 255, only the least significant 8 bits are effective.
Data n
0
n
1
2
3
4
5
6
7
-
-
255 256 257
n+255 n+1
-
-
n+1 n+2 n+3 n+4 n+5 n+6 n+7
n
Column Address
Burst Length
2 words:
4 words:
8 words:
Full Page: Column address is repeated until terminated.
--- Addressing Sequence of Interleave Mode
A column access is started in the input column address and is performed by inverting
the address bits in the sequence shown in the following table.
Data n
Column Address
Burst Length
Data 0 A7 A6 A5 A4 A3 A2 A1 A0
Data 1 A7 A6 A5 A4 A3 A2 A1 A0#
Data 2 A7 A6 A5 A4 A3 A2 A1# A0
Data 3 A7 A6 A5 A4 A3 A2 A1# A0#
Data 4 A7 A6 A5 A4 A3 A2# A1 A0
Data 5 A7 A6 A5 A4 A3 A2# A1 A0#
Data 6 A7 A6 A5 A4 A3 A2# A1# A0
Data 7 A7 A6 A5 A4 A3 A2# A1# A0#
CAS# Latency Field (A6~A4)
4 words
8 words
·
Preliminary
1998
December
15
ETRON [ ETRON TECHNOLOGY, INC. ]
