DS-FND-BSX-PC Xilinx Inc, DS-FND-BSX-PC Datasheet - Page 172

• Manufacturer Part Number: DS-FND-BSX-PC
• Description: FOUNDATION BASE SYS W/SYN EXPRES
• Manufacturer: Xilinx Inc
• Type: Foundation Systemr

Specifications of DS-FND-BSX-PC

• For Use With/related Products: Xilinx Programmable Logic Devices
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 122-1185

Foundation Series 2.1i User Guide
6-16
Instance Names for LogiBLOX RAM/ROM
In the Foundation Express methodology, whenever large blocks of
RAM/ROM are needed, LogiBLOX RAM/ROM modules should be
instantiated by the user in the HDL code. With LogiBLOX RAM/
ROM modules instantiated in the HDL code, timing and/or
placement constraints on these RAM/ROM modules and the RAM/
ROM primitives that comprise these modules, are specified in a .ucf
file.
To create timing and/or placement constraints for RAM/ROM
LogiBLOX modules, you must know how many primitives are used
and how the primitives inside the RAM/ROM LogiBLOX modules
are named.
Note: LogiBLOX does not support Virtex. You can get a Virtex RAM
from the CORE Generator system.
Calculating Primitives for a LogiBLOX RAM/ROM
Module
When a RAM/ROM is specified with LogiBLOX, the RAM/ROM
depth and width are specified. If the RAM/ROM depth is divisible
by 32, then 32x1 primitives are used. If the RAM/ROM depth is not
divisible by 32, then 16x1 primitives are used instead. In the case of
dual-port RAMs, 16x1 primitives are always used. Based on whether
32x1 or 16x1 primitives are used, the number of RAM/ROMs
primitives can be calculated.
For example, if a RAM48x4 was required for a design, RAM16x1
primitives would be used. Based on the width, there would be four
banks of RAM16x1’s. Based on the depth, each bank would have
three RAM16x1’s.
Naming Primitives in LogiBLOX RAM/ROM Modules
Using the example of a RAM48x4, the RAM primitives inside the
LogiBLOX would be named as follows:
MEM0_0
MEM0_1
MEM0_2
MEM1_0
MEM1_1
MEM1_2
MEM2_0
MEM2_1
MEM2_2
MEM3_0
MEM3_1
MEM3_2
Xilinx Development System