IBM0612404GT3B
IBM0612804GT3B
Advance Rev 0.2
128Mb Double Data Rate Synchronous DRAM
Burst Definition
Starting Column Address
Order of Accesses Within a Burst
Burst Length
A2
A1
A0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Type = Sequential
Type = Interleaved
0-1
0-1
2
1-0
1-0
0
0
1
1
0
0
1
1
0
0
1
1
0-1-2-3
0-1-2-3
1-2-3-0
1-0-3-2
4
2-3-0-1
2-3-0-1
3-0-1-2
3-2-1-0
0
0
0
0
1
1
1
1
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
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
8
Notes:
1. For a burst length of two, A1-A i selects the two-data-element block; A0 selects the first access within the
block.
2. For a burst length of four, A2-A i selects the four-data-element block; A0-A1 selects the first access within
the block.
3. For a burst length of eight, A3-A i selects the eight-data- element block; A0-A2 selects the first access
within the block.
4. Whenever a boundary of the block is reached within a given sequence above, the following access wraps
within the block.
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 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 Burst Definition on page 11.
Read Latency
The Read latency, or CAS latency, is the delay, in clock cycles, between the registration of a Read command
and the availability of the first burst of output data. The latency can be programmed 2 or 2.5 clocks.
If a Read command is registered at clock edge n, and the latency is m clocks, the data is available nominally
coincident with clock edge n + m.
Reserved states should not be used as unknown operation or incompatibility with future versions may result.
©IBM Corporation. All rights reserved.
Use is further subject to the provisions at the end of this document.
06K0566.F39350
5/00
Page 11 of 79
IBM [ IBM ]
