10 Integrated Silicon Solution, Inc. - www.issi.com
Rev. A
10/22/09
IS42SM83200D / IS42SM16160D / IS42SM32800D
IS42RM83200D / IS42RM16160D / IS42RM32800D
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.
BURST DEFINITION
Burst Starting Column Order of Accesses Within a Burst
Length Address Type = Sequential Type = Interleaved
A0
2 0 0-1 0-1
1 1-0 1-0
A1 A0
0 0 0-1-2-3 0-1-2-3
4 0 1 1-2-3-0 1-0-3-2
1 0 2-3-0-1 2-3-0-1
1 1 3-0-1-2 3-2-1-0
A2 A1 A0
0 0 0 0-1-2-3-4-5-6-7 0-1-2-3-4-5-6-7
0 0 1 1-2-3-4-5-6-7-0 1-0-3-2-5-4-7-6
0 1 0 2-3-4-5-6-7-0-1 2-3-0-1-6-7-4-5
8 0 1 1 3-4-5-6-7-0-1-2 3-2-1-0-7-6-5-4
1 0 0 4-5-6-7-0-1-2-3 4-5-6-7-0-1-2-3
1 0 1 5-6-7-0-1-2-3-4 5-4-7-6-1-0-3-2
1 1 0 6-7-0-1-2-3-4-5 6-7-4-5-2-3-0-1
1 1 1 7-0-1-2-3-4-5-6 7-6-5-4-3-2-1-0
Full n = A0-A8 (x16, x32) Cn, Cn + 1, Cn + 2 Not Supported
Page n = A0-A9 (x8) Cn + 3, Cn + 4...
(y) (location 0-y) …Cn - 1,
Cn…
CAS Latency
The CAS latency is the delay, in clock cycles, between the registration of a READ command and the availability of the
first piece of output data. The latency can be set to two or three clocks.
If a READ command is registered at clock edge n, and the latency is m clocks, the data will be available by clock
edge n + m. The DQs will start driving as a result of the clock edge one cycle earlier (n + m - 1), and provided that
the relevant access times are met, the data will be valid by clock edge n + m. For example, assuming that the clock
cycle time is such that all relevant access times are met, if a READ command is registered at T0 and the latency
is programmed to two clocks, the DQs will start driving after T1 and the data will be valid by T2, as shown in CAS
Latency diagrams.
Reserved states should not be used as unknown operation or incompatibility with future versions may result.
Operating Mode
The normal operating mode is selected by setting M7 and M8 to zero; the other combinations of values for M7 and M8
are reserved for future use and/or test modes. The programmed burst length applies to both READ and WRITE bursts.
