Answers Database

Foundation F1.3/F1.4 Simulator: How much memory does a simulation require?


Record #3161

Product Family:  Software

Product Line:  Aldec

Problem Title:
Foundation F1.3/F1.4 Simulator: How much memory does a simulation
require?



Problem Description:
Keywords: F1.3, Foundation, Functional, Timing, Simulation,
	  Memory, RAM

Urgency: Standard

General Description:

What are the memory requirements of the Foundation Logic
Simulator and what is the maximum time the simulation can be
run?


Solution 1:


There isn't a software limit on the maximum time for the
simulation, but there is a physical limit in the form of
memory.  For each signal probed/analyzed, every time there is
an event (the signal in question changes value), 16bytes of
memory are required to store the waveform.  This requirement is
above the required memory for operation of the Foundation
tools.	The system requirements specified in our documents are
adequate for most simulations.	However, if the simulation
involves long sim. times and/or a large number of signals
analyzed, additional memory may be required.  This is the case
when you see an error regarding insufficient resources during a
simulation.

Example:
For a 4Mhz clock running for 40ms, you need about 5Mb of
memory, just to store the waveforms. If you observe 20 other
signals that change at ~2Mhz, the simulator will need an
additional 51Mb, requiring a total of 56Mb.  Along with the
tools and operating system, this can overload the resources of
the system.

Solutions:
1. Increase the amount of swap space available to the system.
The down side of this solution is that system performance can
be reduced by increasing dependency on the hard drive.

2. Reduce the number of signals analyzed or the length of the simulation.

3. Install more physical RAM.



End of Record #3161