Specifications
414 www.xilinx.com Development System Reference Guide
R
period
The period is the number of steps in a clock pattern multiplied by the 
step size.
physical annotation
Physical annotation uses just the .ncd file. In this mode, a timing 
simulation model is generated from the physical device components. 
PIM
Physically Implemented Module
pin
A pin can be a symbol pin or a package pin. A package pin is a 
physical connector on an integrated circuit package that carries 
signals into and out of an integrated circuit. A symbol pin, also 
referred to as an instance pin, is the connection point of an instance to 
a net.
PIP (programmable interconnect points)
Programmable interconnect points, or PIP, provide the routing paths 
used to connect the inputs and outputs of IOBs and CLBs into logic 
networks.
A PIP is made of a CMOS transistor, which you can turn on and off to 
activate the PIP.
placing
Placing is the process of assigning physical device cell locations to the 
logic in a design.
PLD
A Programmable Logic Device (PLD), is composed of two types of 
gate arrays: the AND array and the OR array, thus providing for sum 
of products algorithmic representations. PLDs include three distinct 
types of chips: PROMs, PALs, and PLAs. The most flexible device is 
the PLA (programmable logic array) in which both the AND and OR 
gate arrays are programmable. In the PROM device, only the OR gate 
array is programmable. In the PAL device, only the AND gate array is 
programmable. PLDs are programmed by blowing the fuses along the 
paths that must be disconnected. 
FPGAs and CPLDs are classes of PLDs.
post-synthesis simulation
This type of simulation is usually done after the HDL code has been 
expanded into gates. Post-synthesis simulation is similar to behavioral 
simualtion since design behavior is being checked. The difference is 
that in post-synthesis simulation the synthesis tool’s results are being 
checked. If post-synthesis and behavioral simulation match, then the 
HDL synthesis tool has interpreted the HDL code correctly.










