Z01X™ is a high-speed functional fault simulator for Verilog designs. Its high performance, memory efficient, C2™ algorithm combined with its integrated expert test system, Fault Manager™, makes fault simulation of large designs a reality.

Feature List

• Test ordering with redundant test elimination
  

• Verilog IEEE 1364 (1995, 2001 & 2005)
  

• Behavioral, RTL, UDP, gate and switch level
  

• Full timing, path delays, negative timing checks, SDF
  

• Stuck-bt, transition and Bridge fault models
  

• Distributed simulation
  

• Hyper fault checking
  

• Automatic crash recovery
  

• STIL, WGL, VCD/eVCD and testbench stimulus
  

• Flexible reporting
  

• Verifault-XL® compatibility

Test Ordering and Redundant Test Elimination
Prior to fault simulation Z01X performs testability analysis of the design and test suite to determine the quality of each test. Tests are then ranked best-to-worst and fault simulation is begun using the one with the highest Test Quality. After each test is simulated, Testability Analysis is run again and the tests are re-ranked. By running tests in the most effective order Z01X can reduce fault simulation time as well as tester time. Z01X also eliminates redundant tests, often 50% or more of the test suite.
 

A major feature of Z01X is its ability to sort through tests to find near optimal tests. In the diagram above, Z01X eliminated 11 out of the 21 tests provided by the customer thereby significantly reducing tester time.

Language Support
Z01X supports the full Verilog IEEE 1364-2001 language, including behavioral, RTL, UDP, gate and switch-level. No re-modeling of complex modules such as memories or PLL's is required.

Stuck-At Faults
The stuck-at fault is the most common fault model and it represents several types of defects. Z01X can either generate a list of stuck-at faults, including fault collapsing, or a fault list can be imported from other tools such as FastScan™, TetraMAX® and Verifault-XL.

Transition Faults
A transition fault models a signal which is delayed by 1 or more clock cycles. Z01X models slow-to-rise and slow-to-fall transition faults. The transition fault list can either be generated by Z01X or imported from other tools, such as FastScan or TetraMAX. The detected faults from a stuck-at fault simulation can also be used as a starting transition fault list. Multiple clock domains are supported by performing one fault simulation for each clock domain.

Bridge Faults
Bridge faults are used to model two signals that are physically shorted. Z01X supports 4 bridge fault modes, wired-or, wired-and, X dominate and Y dominate. Unlike stuck-at and transition faults, which can be generated from a netlist, the bridge fault list must be extracted from the physical layout.

Hyper Fault Checking
The concurrent algorithm is subject to faults which can use excessive amount of simulation time or memory. These faults are commonly referred to as hyper faults. Z01X has automatic and user-defined checking for hyperactive and hypertrophic faults. A hyperactive fault can cause excessively long simulation times. A hypertrophic fault can cause excessive memory usage.

Distributed Simulation
Fault simulation can be very CPU intensive. Distributing the fault simulation across multiple CPU's will result in a near linear reduction in wall clock time. Each CPU simulates the complete design with a portion of the fault list. A fault simulation which takes 12 hours on a single CPU would take approximately 3 hours using 4 CPU's. Distributed fault simulation with Z01X can easily be setup using named hosts or with Platform LSF® from Platform Computing.

Automatic Crash Recovery
Z01X automatically re-starts any partition which fails in a distributed simulation with very little loss of data. Should the master process fail the fault simulation can be re-started and Z01X will automatically resume from the point of failure.

Stimulus
To accurately model the tester Z01X accepts STIL or WGL stimulus. VCD/eVCD or a Verilog testbench can also be used. Parallel loading can be done with STIL or WGL for verification of ATPG scan vectors. Z01X automatically verifies correct simulation when using STIL, WGL or VCD/eVCD stimulus.

Verifault-XL Compatibility
Z01X supports many of the Verifault-XL system tasks, such as $fs_add() and $fs_strobe(), as well as Verifault-XL compiler directives, such as `enable_portfaults and `suppress_faults.