
2-5
Architecture
Lattice Semiconductor
LatticeXP Family Data Sheet
The Lattice design tools support the creation of a variety of different size memories. Where appropriate, the soft-
ware will construct these using distributed memory primitives that represent the capabilities of the PFU.
Table 2-3shows the number of Slices required to implement different distributed RAM primitives.
Figure 2-4 shows the dis-
tributed memory primitive block diagrams. Dual port memories involve the pairing of two Slices, one Slice functions
as the read-write port. The other companion Slice supports the read-only port. For more information on RAM mode
in LatticeXP devices, please see details of additional technical documentation at the end of this data sheet.
Table 2-3. Number of Slices Required for Implementing Distributed RAM
Figure 2-4. Distributed Memory Primitives
ROM Mode: The ROM mode uses the same principal as the RAM modes, but without the Write port. Pre-loading is
accomplished through the programming interface during configuration.
PFU Modes of Operation
Slices can be combined within a PFU to form larger functions.
Table 2-4 tabulates these modes and documents the
functionality possible at the PFU level.
SPR16x2
DPR16x2
Number of Slices
1
2
Note: SPR = Single Port RAM, DPR = Dual Port RAM
DO1
DO0
DI0
DI1
AD0
AD1
AD2
AD3
WRE
CK
DO0
AD0
AD1
AD2
AD3
DPR16x2
SPR16x2
ROM16x1
RDO1
RDO0
DI0
DI1
WCK
WRE
WDO1
WDO0
WAD0
WAD1
WAD2
WAD3
RAD0
RAD1
RAD2
RAD3